Some states offer free prenatal care to EVERY pregnant woman regardless of financial status. GA & NC are 2 I know of for sure.
Look for a federally qualified health center that does ob. They have to see you regardless of your coverage and will charge you based on your income.
You should call your insurance company and see if they back date.
I been taken prenatel vitamins, and I have been to the doctor to get a blood tests but that's about it
Try to get into a free clinic or planned parenthood just so you can get some healthcare and possibly an ultrasound. They'll work with you. Don't wait until your insurance kicks in. It's important to have some kind of early medical care.