Your story is shit.
Some people can't actually write.
Of course this isn't you. Your mum loves your novel. Your writing group think it's great (as long as you say the same about their sample chapter). Vanity publishers are falling over themselves to make special offers that will make publishing your opus a breeze! They even want to give you FREE copies of your book with every publishing package you buy!
All his praise and attention leaves amateur writers completely blind to the fact they can't write for shit.
We all know a lot of people who call themselves "writers" or "authors" and yay for them. But think of all the things you do on a daily basis - do you refer to yourself by something you do, but don't get paid for?
Every time a "writer" declares themselves as such - inquire as to their publishing history. If they haven't got a publishing history they shouldn't be calling themselves writers any more than a teenage boy should be calling himself a "masturbator".
Not actually being able to write is however no barrier to a writing career earning real money. The important step that is so easily skipped over - is learning how to write. It's up to the individual how they learn to write. Take a class, get a degree, read hundreds of books, and write every day. All standard advice from famous authors for hundreds of years.
The key thing is that no one just writes – you learn it like any other skill and keep learning it until you stop doing it.