Risks involved
Neuro, I'm not a doctor or anything, but since you're only 18, propecia seems like a drastic intervention, you might want to consider that in deciding whether to stop. These drugs can have serious side effect, I realized this when I decided to try Prozac since I was slightly depressed. It worked, but the damn medicine made my most important organ not function properly, it was really scary and fortunately wasn't permanent. I figured I'd rather be depressed than to have that not work. I also had a very good friend who got very seriously and permanently screwed up by psychiatric drugs. Overall, I think people, and especially Americans tend to take these medications too easily and downplay the side effects. I don't mean to identify a particular nation but the fact is that in America they give antipsychotics to thousands of children for behavior problems (WTF?), I would definitely not use any hormonal treatment at your age if I was you. Don't mean to scare you though, good luck.