Yes, keeping kesh is hard. There are so many reasons given for keeping or not keeping one's hair unshorn. For me there is only one reason: my Guru asks this of me and I love and trust my Guru. One reason that is not a reason is fear of going "to hell or being sinful." Fear is usually a bad reason for doing anything; it is doubly so here.
A few weeks ago, my medical caretaker, Irene - yes, good ol' TGI, asked me what would happen to me if I cut my hair. Would I be thrown out of the Sikh religion? Would I go to hell? Would God be very angry at me? The answer was a definite NO to all those questions. The worst that would happen to me is that I would no longer be a(n aspiring) Khalsa until and unless I took Amrit again. Of course, some more traditional members of the sangat would condemn me. It's also likely that those of the Mona Morcha - who believe that kesh is meaningless and/or outdated and should be discarded - would congratulate me.
For me personally, I would be betraying something that is deeply meaningful to me, no matter what opinion others may have. For me, keeping kesh is an integral part of being a Sikh. Without it, I would be missing what is to me a vital part of the experience of being a Sikh. In high school, especially, I caught a lot of flak not shaving my legs and armpits. That only made me dig in and hold firm. "They think they can make me be like them? Ha! That's just not Mai." I cannot say that sort of defiance is good or bad; I can only say that is me.
Sanget ji, I frankly think your "reasons" are excuses. I am not trying to be rude to you, but every "reason" you give can be easily overcome. As has been said there have been Sikh soldiers, athletes, firefighter, Sikhs in every legitimate pursuit who have kept kesh. Please be honest with yourself. At 16, you probably feel grown-up or nearly so. That's natural, but you are still really very young. At your age, peer acceptance - which I believe is really what this is all about - can be paramount. My suggestion is that you look deep inside yourself and make the courageous decision to pursue "truthful living" whatever that means to you.
On a very personal note, I have come to love my hair, all of them. And I personally would love to see every Sikh seeing and understanding the meaning of keeping kesh, enjoying their natural being. I admit that I love the Khalsa roop. I find men and women who "look like Sikhs" to be extremely attractive. However, I am realistic enough to know that is not going to happen.
So Sanget ji, I throw it right back to you. What is "truthful living" to you? I can answer only for myself. You must find your own answers.