Twenty years ago, I published my first book. My 34th is due out next spring. Here I reflect on the grit and the glamour of the writer's life - and on how much things have changed in since 1994.

Twenty years ago this week my first book was published - Unlawful Carnal Knowledge: The True Story of the Irish X Case was subsequently banned in Ireland, which made it an overnight success north of the border.

As a journalist on the Daily Telegraph, I was working full-time but took the week off to promote my book and enjoy a series of low-key celebratory events with my agent, my editor, and a few close friends who presented me with champagne and flowers. I signed some copies at a bookstore in Belfast (after a bomb scare), and my editor in Dublin took me for a splendid lunch at the Shelbourne Hotel.

In 1994, there was no mention of ebooks or interactive electronic editions, and neither Amazon nor Audible existed. I wasn't expected to hire a publicist, choose which voice-over actor I'd like to recite my work, or spend hours each week updating my social networking pages. I wrote a piece for the Sunday Times and appeared on Irish telly and the BBC, but nobody expected me to take part in interactive Skype chats with book clubs around the world, or attend public speaking engagements where I'd be cross-examined on my subject matter.

Life seemed simpler then.

In the two decades since my first book was released, I have had almost every publishing experience one can imagine. There have been gruelling and not-so-glamorous international book tours with horribly early starts, glittering launch parties in New York, London, Hollywood and Suffolk, and hours trapped in airless radio studios doing down-the-line interviews. I've been filmed for the NBC's Today show, TV stations in Paris, Gibraltar and Rome, sat in on Pebble Mill and The View, and had a Hollywood movie star unexpectedly pick up the bill for the Manhattan launch party of my first novel, The Sense of Paper.

Movie rights have been repeatedly optioned on Tomorrow To Be Brave, my book about the only woman in the French Foreign Legion, and I was with actors Caroline Quentin and Kevin Whately at the premiere of the TV mini-series that was adapted from my book Footprints in the Snow. I've appeared on BBC Radio 4's Woman's Hour to talk about the first Gulf War. I've given talks on the same subject to Government officials and sat gratefully in the green room of countless TV studios while my clients such as Goldie Hawn, Barbara Sinatra, Deana Martin, Haatchi & Little B, and Uggie the dog went "out front" to promote our work.

I've been deafened by hysterical fans who'd queued all night for the signature (or pawprint) of a star whose memoir I'd just penned, and I have criss-crossed the world First Class to stay in the sort of homes and hotel suites that most can only dream of. I also lived for 18 months in a crummy pension on the outskirts of Paris, resided in a smelly B&B in Humberside, and made my home for while in a Travelodge in the Home Counties.

To keep me on my toes, a television crew from the Swedish equivalent of Newsnight recently flew in from Stockholm to film me speaking about the history of post-traumatic stress disorder because of my book Shell Shock, and later this year I'll be giving a talk to more than 100 National Trust volunteers to mark the centenary of the end of the First World War.

From my clients, agents, and publishers over the years I've been presented with a variety of gifts including a shopping trolley full of sex toys, a Cartier watch, a Harrods pillow, a straw hat, a designer handbag, hampers, a solid gold bookmark, and enough flowers to fill an abandoned Borders store. Publishers have presented me with several framed book jackets as well as beautiful leather-bound copies of my titles, and I have a gratifying number of framed bestseller lists mounted under glass.

In this my anniversary month, my 33rd book has been published - The Beat of My Own Drum, the ghosted memoir of the American musician Sheila E, whose childhood sexual abuse almost ruined her life until she found healing through music. I represent myself these days, and the editor who worked on the book with me was recently made redundant, so there were no cards or flowers from her. If it weren't for my long-suffering husband there would have been no celebrations, and only a few of my friends even appreciated the milestone.

Meanwhile I sit in my garret in Suffolk, completing my 34th book - Born Survivors - a Holocaust memoir that was discovered, researched, written and agented entirely solo. The research for this project has taken me to San Francisco, Nashville, Auschwitz, Prague, and Bratislava, and the book will be launched at the Mauthausen concentration camp in Austria next May, followed by a three-country book tour and months of publicity.

To keep my American publishers happy, I recently had to complete a 10-page questionnaire that asked me to provide a comprehensive resumé and reviews, several hi-resolution author photographs, and the name and address of my publicist. I was instructed to give a full list of my titles, including all editions, dates of publication and numbers of copies sold (by my reckoning over a million all told).

They wanted the names of any academic organisations I belonged to, my media contacts, lists of any honours and awards, and articles I had written. They asked for an explanation of how I came to write this book, a snappy précis (including my assessment of its relevance), plus the flap copy, my opinion of its likely market, potential readers, lists of any known competitors, and an assessment of how it might "benefit" my audience.

I am to name people to whom advanced bound galleys should be sent (I suggested Stephen Spielberg), which awards I'd like to be nominated for, and the name of the speakers' bureau that represents me. They want to ensure that I have a Facebook and Twitter presence, they need my Skype and FaceTime details, and asked what I've posted lately on Pinterest, Voxer, Tumblr, Google and any number of other sites, some of which I have never heard of.

They automatically assume I have a website but would like to know whether I also have fan pages, engage in live chats, message boards, blogs or provide email newsletters. Tellingly, they didn't ask for the numbers of the phalanx of assistants I'd need to employ if I were to keep on top of all this, as they seem to be suggesting.

Twenty years is a long time in this business. For 17 of them it has been my sole source of income, and of that I am very proud. Many of the changes that have happened have crept up on me while I just kept writing and trying to do what I do best. It is only on such landmark occasions that I can pause to reflect on the evolution of the industry and wonder where it might take me from here.

With many of my ebook sales outstripping hardbacks for the first time, and the digital age firmly in charge of both how I work and promote myself, I have had to evolve too. The good news is that there is still a hunger for words in whatever shape and format they take. Here's to the next 20 years of writers like me still wanting to write, and readers still wanting to read what we have written - when we're not on Voxer, that is!

Born Survivors by Wendy Holden will be published by Little, Brown May 2015.

www.wendyholden.com