How do I stay with that girl?

Hello,in this year I met a girl that's really make's my life great again.I was stucked my life I don't have a job I don't study at nothing I don't do nothing at all.I wake up everyday trying to get some job or anything that make me profit to do something but nothing works at all.When one day this girl text me from nowhere,she start talking about my post on Instagram and about this day I didn't know what I'll experience on my life.After a few months we started getting to know each other more and more getting to know each other every time we met. Until 2 months after we were together I was alone and home and technically from the situation I figured it would be the day I would have a stronger relationship. and open the sexual side.But from this day on everything went wrong and no matter how or what I did to solve the situation I just made things worse.We have tried many times to make love but for some reason I have failed every time until it gets to the point that we can no longer take this situation forward.I sought all kinds of medical help from this point where I failed and amazingly nothing seems to be wrong with my physical health.And we get to this day where we talk every day, I can talk to her about everything but I still fall in love with her and I believe I can't reach this dream anymore.And talking about today, today was my birthday and I invited her to join the family lunch with us and look I'll tell you I never felt so happy and wanting to kiss someone like today.I know I have to move on but I don't know what to think anymore, I think I got lost because I couldn't evolve with my great love.So sorry about my english or something wrong but Idk much about. This problem seen to be easy for most but for me It's killing me inside.