Think you got BPH a little early but it's not a big deal either way. I suppose you had a weak stream, stopping and starting urinating was hard? You can have an operation too but they prefer meds first. Secondary hair benefit sounds perfect. You should have taken it a while back even though your hair is pretty good. Sort of like an insurance policy for hair but seems no harm is done. Have your hair genetics to thank for that.
And that's why I don't take any credit for my "solid plan" as you say. It's all luck. I don't have an aggressive pattern, thick hair naturally too, just was a case of getting on finasteride early and having a transplant. Genetics. So crucial not just physically (looks) but mentally (intelligence and no red flags).
I've done well at school and subsequent career - lots of sacrifices. But above it all, I'm most grateful for being attractive and keeping a full head in my youth and most likely will for next 20 years. You may have OCD over it but serious hair loss does hit the self esteem, can cause quick deterioration in aesthetics like no other thing. You have nothing to worry about mate, you're practically full with native hair - minor male pattern baldness at the front. In fact, the majority of this section has typical hair loss sufferers and are doing well even with current treatments.