Was your DS planned or an accident?
And how old is your partner? Has he got a lot of already established family?
This is sadly quite common. An 'oops' baby with a new younger partner that throws everyone's noses out of joint in the family who are already established.
You don't have any leverage here.
It's all very well to be demanding this and that, but if the baby was an accident you've sort of made your own bed.
You have a sugar daddy of sorts. He's providing for your DS and for you while you study to earn your own money.
He's like a benefactor... if you want childcare for your DS, I'd forget whining about how he hasn't disclosed his salary etc. That's not how to play these men.
Just ask for it up front and he'll more than likely have the money and pay...
There's a lot of moral chest beating on here but if you split, what have you got ? you're not exactly in a strong position financially. He's got all the cards.
I'd probably bite me tongue, graduate and then leave but then I've always had a high pain threshold emotionally and no doubt this isn't the best advice. But for now you've got a good set up financially to study and then do a runner...
Do you love him? Or do you love his money?