One thing you got going well is that she is also a virgin. Maybe her expectations will not be much about sex. The main thing I would worry about is the anxiety that you may be causing yourself thinking about it. This may cause you problems getting or keeping an erection.

I was in the same shoes as this when I was in high school and lost my virginity. I was not able to get an erection because I worried so much. I gave it another try a week or so later with her and everything operated as should. Experiment around some and find the things you both like. foreplay can definitely help. Also, I tried \ an and still try to utilize performing oral sex to try to make up for the other short time.

In the meantime, if you want to practice. Try extending out your masturbation time. If you last 3 minutes now. Try for 4 minutes next week and five the week after. Try some slowing down practices while by yourself to see what best fits you. I know first hand it is easier and less streesful to try these own your own and without an audience. Not to mention they can be fun