Hi whippino,
You've still got a good amount of hair, but what concerns me is that your crown loss looks to be potentially quite extensive. If it progresses to thin down the sides and back then planning an ht can be a complicated process. Finasteride could help to prevent this or at least delay it significantly, so it's certainly worth considering, though as Bigmac says, there can occasionally be side effects.
I'd definitely recommend you arrange a consult with a reputable clinic to discuss things and formulate a 'plan of attack'