Hello Si, this is my first post here, reading what you wrote inspired me to post since I went through very similar emotions. I'm not feeling very articulate but hope I can write something half decent

I think I might be a little like you in that I am quite sensitive to others and my emotions tend to be all over the place.
Anyway I discovered I was losing my hair in my late teens and like a lot of people here I felt it was the end of the world. I'm now in my early 20s. About 6 months ago, after a lot of soul searching and reading sites like this I began to accept the idea of hair loss and to worry a lot less about it as I now felt I had a decent solution; to shave it all off! However I was still very anxious about taking the final step. Like you I tried to run the idea by family members and friends in the hope their replies might raise my confidence to do it, but got negative responses from every one of them.
So after months of fence sitting I had a long break from university and decided this would be the best time, especially as I was still worrying about it and I didn't want it to affect my life any more. Once I had decided I had to have it done right away it still took two weeks of a great deal of an anxiety and putting it off 'til the next day. I finally got the courage and went to the barbers. Even as I was sat there waiting I thought, I'm going to chicken out, especially as it was busy and had an hours wait! So I was sat in the chair, had a big mop of hair on me head, the barber asked what I wanted doing and seemed to think I was a little mad once I told him I wanted it shaving on zero

So he did the deed and shaved it on zero. Once it was done I instantly got positive comments from the barber and other people waiting, which raised my confidence, although I was already feeling pretty confident for some reason.
Now to the part I was most worried about, my close family's reaction. There was palpable shock at first, especially from my sister who seemed to stare at my head open mouthed for about 5 seconds. After the initial shock I got positive responses from all of them. It seems many people don't like the notion of head shaving, that to try and convince them before hand will ultimately be in vain. It's something you just have to go ahead and do, then show them in order to get their acceptance. As for other people, you might be surprised at how a lot of people actually don't care. I've seen a few friends from uni since, in some instances despite having a head just shaved on zero, I'm the one who has had to steer the conversation in the direction of my hair. Many have even said they haven't even noticed I was balding; it's true what they say that we magnify our own problems a 100 fold.
Obviously if you feel that you have to wear a hat much of the time it is already affecting your life a great deal. And as you say you are young, these aren't emotions you should be experiencing at your age. If you're already feeling a lot of anxiety about losing your hair I can't imagine how shaving it will make the problem any worse. The only thing you have to overcome is the initial head shave and the resulting shock from your family. A day basically, and hopefully after that you should begin to feel more confidence. As for your close friends with long hair, hmm I know it is difficult, especially as at a young age we're at such a vain stage in our lives. As I say you might be surprised at how much other people don't care. I actually got a buzz from the idea that I was doing something so unique from them, something that took a lot of courage. Of course if they're half decent friends they like you for your personality, not how you look.
Oh, don't forget to give it the 30 day trial before making any decisions.
Anyway, I guess this also serves as my introduction to the board, and I hope it helps a little. Please post back with your thoughts and how you get on.