Yep, I have a son, we're not married. It's hardly uncommon.
Our money is joint, it's OUR money, not mine or hers.
This (except in my case it's mine and his!) - we earn quite different amounts, but it all goes into one account and everything is joint. No concept of any person paying x or the other paying y.
Mortgage is in gf's name, she pays it in full.
I cover all bills and food.
I earn about 25% more than her, so it balances.
Wouldn't be keen on that!
That's changing the living arrangements though as not many people will have children born outside of wedlock, and wedlock changes the legal perspective on it all anyway.