1. My father also had prostate cancer, and I followed PSA until it got over 4. I waited 2 months from decision for biopsy until appointment was available. I assumed I had cancer until proven otherwise (which of course was the case.) Use this time to learn about possible treatments and ways to manage side effects.
2. Since you are immuno compromised and have had infections as a result before, I would be very assertive with your desire for minimal risk, and don't rest until you can get a transperineal biopsy. I had a transrectal with no pain or complication, but in your case, caution is the best approach.