You sound like my bf and she sounds like me

I honestly believe if you really care for this girl which sounds to me like you do. For a reason you're thinking about the stuff you did and should have done. She probably still cares for you. Don't let a good thing go, but only if you're willing to actually give her your attention and time. We can either make it work or let go and always think "what if" so just call her and speak from your heart.
Good luck