Just try finasteride, you probably won't get any sides and if you do then just quit and they'll go away in a few months or less. You have male pattern baldness and finasteride is the only thing that is effective at preventing male pattern baldness long term. You have a good chance of regrowing some hair, maybe not all, but you'll probably notice a decent improvement. You probably won't regrow all the hair you've lost. At your age you have an aggressive case, without finasteride you'll probably be pretty bald in a few years time, you should at least try it. It probably won't give you side effects, and it probably will regrow hair and help you maintain what you have for a few more years, maybe longer.