You two better get that under control before the baby comes. You can't just not feed your baby because you don't have money. That's not an option and isn't acceptable. Apply for food stamps if you have to. Move back home if you have to.
It's easy to say "things won't be that way when the baby's born" but will that be true? You're having a hard time now with just the two of you. Why would things be any easier with three? Babies are very expensive. You need to decide now if you'll be able to support your child, especially since you're having trouble supporting yourself.
Apply at .Mc.Donald's. Babysit. Wash cars. Walk dogs. There is always
something out there. Going hungry isn't fair to your child, who is relying on the nutrients you put in your mouth so he/she can grow. Get your priorities straight and don't rely solely on your boyfriend's "big job". Take care of your business. You're going to be a mother.