NSFW erection problems

This has often come up from time to time for me and it just makes me feel super inadequate sexually. I (m, 23) have been with my bf (22) for 5 months. Things have been great overall.Sexually, I am vers bottom. I'm very comfortable bottoming, etc. my problem is in topping. I have almost no experience topping and I'm craving to learn. My bf is more top and not super comfortable bottoming. I've tried topping him three times and all were unsuccessful. He is very tight but another problem is with my erection. I'm uncut and very sensitive and I can't sustain an erection hard enough or long enough for penetration.We've done lots of foreplay, etc. but I'm starting to feel very sexually inadequate with 1. The quality of my erection. And 2. My lack of experience in topping. It's been a massive hit to my self esteem.I've experienced some sexual related trauma in the past that I'm sure is affecting everything. I've talked with my partner about these things and it's super embarrassing and can easily pull me out of the mood.In short, I don't know what to do about my erection. I've looked into doing kegals but I'm having trouble locating the muscles. I kind of want to try a viagra once just to see how it impacts my erection (and hopefully rewire some of my insecurities around it). The problem is getting one.I don't have any issues reaching orgasm. My refractory period is almost nothing. I struggle with anxiety so I'm sure the performance anxiety thing is present. Any advice would be so helpful. Thank you for reading.