New pregnancy. Delivered at 34 weeks last time.

I just got a positive... like just an hour ago... I'm in BIG BOY denial. I've been having low blood pressure and nausea for the last two weeks. Today I'm having cramping and I took the test. Boom. Pregnant. My son was born at 34 weeks and I have to see a MFM for this one. I dont believe i am pregnant yet... but can you all tell me your experiences with Makena. I have to have them and I'm just... I don't feel like I actually am at all???? I'm in such shock sorry if this sounds long winded and weird.