I guess you're the us, because here in australia you'd be covered under government health care, but do you have health centres/community advice centres? Or could you go to an er for some advice/guidance??
Another possibility is that there are mother's/new mother's groups on-line that your girlfriend could join, they might be able to help with practical (if not actual medical) advice.

Thank god you know that you have to go to the doctor sooooonnn ! Can you get extra insurance? Or maybe if you guys live togeter you can get medicare, check this ...

Http://www.Medicare.Gov/

I think you need to check in to "medicaid", that is why it is there, for people who need the assistance in emergency situations. It makes me so mad when people rely on the welfare system habitually just because it's there, but in your case, it sounds like you really need it! Call your local division of family & children office and they will set you up with a case worker who can get you started. If worse comes to worse, and they cannot help you, hospitals and doctors are usually very helpful in setting up payment arrangements. Goodluck!

~kate~