I would recommend watching a YouTube channel called
The Hair Loss Show, I got most of my information from there. They're very knowledgeable doctors and one of them was part of the research team for the Finasteride study. They will explain to you what finasteride does in the body, potential side effects and much more. They talk about Minoxidil and other treatments as well, so you can decide what sounds the best for you. Go to your dermatologist and ask about finasteride, 18 might be young but you can customize the dosage to a lower amount (3 mgs per week). The amount of DHT blocked is essentially
the same as the 7 mgs per week as there are diminishing returns after a certain amount of finasteride.
If you don't want to do too much research then this is the short answer
Finasteride, Dutasteride: Stop hairloss. There is also potential of regrowth, strengthening and thickening of the hair follicle after about 2 years.
Minoxidil (tropical) and dermarolling: does not stop hair loss but increases blood activity in the areas you apply them to, thus encouraging hair regrowth.
P.S. you're going to see a lot of threads with people talking about side effects for Finasteride but keep in mind that most of these are likely
placebos. Not saying that it's not possible to get side effects but at a low dosage such as 0.5 mg per day it's highly unlikely. Side effects are also
reversible so don't freak-out if you feel like something is off, you can just stop the drug.
Bonus P.S. when you take finasteride or minoxidil you will experience an initial shedding phase were your hair will fall out faster than ever before. Don't panic when this happens and please don't stop the treatment. This is actually a good sign that the drug is working and that the your hairs are entering the hair growth cycle.
Best of luck!