Hi.
You’re asking me many questions which only YOU can answer. How can anyone else possibly know how you feel? It seems to me you already have the answers. Let’s look at the facts as you’ve detailed them:
1. You don’t enjoy penis-vagina (p-v) sex with your girlfriend
2. You don’t enjoy giving her oral sex
3. The only way you enjoy sex is when she gives you oral stimulation
Looks pretty clear to me: you don’t want to be sexual with this woman. Why is that, I wonder? Something about the intimacy of p-v may be problematic for you. Or you're not receiving enough stimulation during p-v. There are lots of possibilities, and it’s up to you to figure out which ones are pertinent.
You may be conflicted about being sexual with her, or p-v with her is not satisfying for you, or there may be some unresolved issues in your relationship, or perhaps you’re angry about something. In addition, you may be using a condom during p-v that is too thick and is thus inhibiting your ability to feel stimulation. Take some time to sit back and contemplate these issues to see if any resonate with you. Best of luck to you. Dr. J