Hey campbell, your situation is very similiar to mine. I first noticed hairloss at when I was 17 and a half (I'm 19 now), I just now decided to start treatment, two years later. Luckily I still have alot of hair, so I believe I will be able to keep it and possibly regrow what I have lost over the last two years.
You are the only one that could know if you have hair loss or not. When I first started losing my hair, I thought it was just a phase as well, that it would eventually end. It never did.
My advice to you is this. Keep the Rogaine (Minoxidil, which is the active ingredient of Rogaine) stored away for a while. Go to
http://www.unitedpharmacies.com and order generic Propecia, called Finpecia. Propecia, Proscar, Finpecia, Fincar, and various other simliar drugs all contain the active ingredient Finasteride. Finasteride basically lets you keep your hair as long as you take it. Cut all the Finpecia tablets in half, and take half a pill a day, which is .5mg. Doing this will decrease the chances of side effects, but still be just about as effective as the regular 1mg dose, there are some studies that say it is just AS effective as 1mg. This is what I am currently doing. Doing this will also save you a crap load of money.
Nizoral. It is an important part of any regimen as it has been shown to have an affect similiar to 2% Minoxidil in regrowth properties and clear away some DHT from the scalp and also reduce dandruff and inflammation of the scalp. Get this and use it once every two days.
Go to froogle and search for Tricomin. Tricomin is a copper peptide that has been shown to enlarge the shaft of the hair follicle and enable a better environment for hair to grow. Get a bottle of that and apply it once in the morning and once at night. Search for it and see how to apply it here on the forums. Don't use to much, if you use it right, one 55 dollar bottle could last you up to 6 months, which is not bad at all.
If you want even more in your arsenal, go for topical 5% Spironolactone. I have heard it tends to be difficult to apply with longer hair, so apply it once at night one hour after Tricomin. It is similar to Finasteride but it is used topically, adding this to your regimen will only further increase your chances of holding on to all of your hair and even having regrowth of already lost hair. You can get Spironolactone from
http://www.minoxidil.com , you will have to e-mail them first and request a prescription for it, they will send you a form via e-mail that you have to fill out and mail to them along with a one time fee of 20 dollars so that you may obtain the prescription for spironolactone. Once you do that you can order as much stuff from Dr. Lee as you want.
Later on down the line, say 8-10 months after performing this regimen, evaluate your progress. Take pictures every month of your hair and see how it is doing. If you feel that you want even more, add the Minoxidil back into the mix. If I were you, I would either get Rogaine foam or Spectral DNC, I would go for the Spectral DNC over the foam, but that's just me.
Oh yeah, I also wanted to add a little bit more. If you are not already, adapt a healthy diet (avoid as much processed food as you can, such as chips, sweets, soda, etc., drink alot of water), and get to the gym. Check out
http://www.bodybuilding.com for alot of information. There are alot of morons there, but also alot of quality informants too. Start taking a multi-vitamin everyday, along with at least 2 tablespoons of flax oil.
Good luck man, I was in your position and I know what it feels like, but know that you can and will keep all of your hair and possibly more if you start treatment right now. Don't wait till your in your 20's, it could be to late by then. Just remember it's not bad taking this stuff, you didn't choose to start losing your hair, it's genetic. Every person in this world has their problems, so don't sweat it.