First of all, this is really normal, IMHO. I had three kids. It's normal not to be thrilled when the baby cries or fusses. Your hormones are really swinging and you're getting back on meds.
I had rough pregnancies off my meds. After I had the babies and a small amount of time passed...a few weeks...I felt really good.
You really do need some help and support. Is the baby's father taking a shift so you can get some sleep? Can he do laundry? Can you get take-out food a few nights? Do you go to a church that could send a volunteer over? Speak UP and get some help.
Getting sleep is hard for "regular" new mothers. Bipolar moms REALLY need sleep. Tell your man things will be a lot better if he helps out.
My kids were three years apart. Make sure not to have yours too close together. You want one potty trained before the next one shows up. PM me if needed...I understand.