I hate to say it, but it looks like male pattern baldness to me.
I getcha on the head thing. My head is rather small, so I don't want to lose the "volume" that hair adds to it. So far, I've been lucky. I have a very noticeable male hairline, and my hair has thinned out a bit, but I don't appear to be balding just yet. Maybe when I'm older. But I think that most guys who do go bald start showing it by my age.
You might look into topical Rogaine, but I think it's only for thinning at the crown of the head. And I don't know what effect topical Rogaine has on your T. I do know that the finasteride pills can seriously mess with transition. Some of my effects slowed down--now that I'm off it, my beard has thickened and spread a bit, and the body hair is coming in more--but I was willing to risk that for a while until I decided what to do about my hair. I just needed to get used to the idea that I might be going bald. I wasn't planning to be on finasteride forever. Would you be willing to slow down your process if it means keeping your hair?