Most Helpful Guy
"My gut is screaming at me to call off the wedding and reevaluate our relationship."
Listen to your inner voice. If you're having doubts now, it's not going to get better over time. Marriage is difficult enough without obstacles like the kind you're describing.
Most Helpful Girl
The fact that you are seeing the red flags and showing concern is admirable. Seriously. How much does he contribute to the chores and waking up to feed the baby? If the weight is not 50/50 do make arrangements to go back to work and place some of that burden on him. Show him how it feels to have delivered a baby and being asked to abandone it and further exhaust yourself to pay a bill. And I hope you take that time to save up, get ahead, and move out on your own to where you will not need him to help pay your and your baby's bills. That's the prideful woman in me talking.
For now, this baby binds you for the next 18 years.. at least. Marriage can wait. Marriage does not magically change people for the better. Stand your ground.