Well he won’t change and you won’t dump him. So your only other option is to stay with him and be miserable.
As @BansheeOfTheSouth says, have a baby with him and then come back here to complain that he never cares for his baby and moans that you don’t keep the house clean enough, cook often enough and give him enough sex.
In fact , why don’t you give up your job to be a SAHM with him? Then you can also complain that you can’t leave him because you and your two kids are now financially dependent on him.
You can post here about how you thought he would change once you had a baby ( hint = he won’t ). And that you were sure he’d make an amazing dad because he was posting all over his Facebook about it and going out with his mates every weekend to celebrate .
Or you can just skip the next 5 years of misery for you ( and 20 years of misery for the baby you might have with him ) and DUMP HIM NOW.
Because I’m afraid it’s not all about you and what you want, it’s about your 6 yo child . Yes I know that’s harsh and you are only 25. But when you chose to have that baby aged 19 you chose to put them first , because that’s what being a mum is . Yes men get to fuck off and leave women holding the baby and it’s not fair but that’s biology.
So you have to make an adult decision and chose not to be a fuck buddy to your waste of space ex. You deserve a lot better and so does your child.
Dump him now. Use your child free nights to have fun with your female friends. Work on your career and qualifications and make a secure financial future for you and your child.
And don’t try to marry or have a baby with a bloke in his 20s, whatever weasel words he uses to get you to shag him and feed him. 99% of men that age have no intention of settling down, why would they? But many of them are prepared to use a vulnerable single mum for their own ends.
You are at a different life stage than most men your age, if you want to marry and have another kid you need to wait until your 30s until men catch up.
I know I’m being very blunt but you are too trusting by half and you are going to get used ( yet again I suspect ).