D.W.
You can't get SSI for pregnancy. But since you do qualify for Medicaid you should also be able to qualify for WIC and food stamps. They are separate entities so you will have to apply for both. Your doctor's office should be able to help you with WIC and check to see if you can apply for food stamp benefits on-line or if not you will need to locate a service center to go apply. Medicaid will completely cover the prenatal care, the birth and post-pardum follow up visit for you so you don't need to look at making any changes there.
And you get thru it by cutting major corners, drop all the non-essentials like cable tv, internet (you can use the internet at the library for free), cell phones, eating out/eating fast food, you use coupons, cook at home, don't buy any non-essentials-no new clothes, etc. Look at where you are spending money now and see what you can cut. My husband was in school forever so I cut corners everywhere I could to make it.