[JPDakota]

I have never been in your shoes. As an adoptive parent I can give my view. I would never have considered adopting a child whose mother wanted to and was able to parent. It just would not have been right. As an adoptee, I think would have been very disappointed if my birth parents had changed their mind right after relinquishment and didn't make that known or do anything about it.
You should parent your child unless there are no other options. There are lots of resources out there for you and your baby, and with a supportive family you'll do fine. Parenting is pretty scary at any age, by the way. You'll be great because your primary concern is your child.

Edited to add a clarification.