Why don't you just try finasteride? You have, nothing to loose, except your hair. Try it and if side affects will occur you can stop the treatment.
I am on finasteride now for 5 years and could keep my status almost stable with that med. Now i am 35 , but i thout about taking finstaderide since i was 23. So, it took almost 7 years until i was 30 for me to really buy it, because i had the same doubts like you. Now i really regret that i didn't start earlier beacause it could have saved me a lot of my hair, at an age where i needed it even more than now.