The decision to wear a hijab should always be yours, you should never be forced to wear a hijab. Forcing something on to somebody in the name of Islam is totally unislamic as in Quran itself it is clearly stated: "
There should be no compulsion in religion" ( 2:257). Unfortunately some people do force their girls to wear hijab, because of their "honour" in the society (i.e. Somali society), but it is unislamic. Religion is a matter between you and God only, if you are not wearing your Hijab for Allah, then do not wear it for people.
I personally think a girl should wear a hijab when she personally feels ready for it, it is when she has reached that "advanced spritual state" in faith. What I mean by that is that the basic thing in Islam is the belief in the One God and the relationship with God i.e. Salah ( prayer). Once you believe in Allah and are close to Him you will really come to a stage where you would want do anything for Him.
Every commandment in Islam has a reason, ultimately to our benefit.
Hijab comes as a result of that spritual connection with God, out of modesty. As someone who wears a hijab, I personally want to be recognized as a modest, God fearing person, not "available" to the other sex.
I know some girls who stopped taking the hijab. At first the "freedom" attracted them and they took off their hijab (not that I am against it), then they took another step and started drinking, then another step and left Islam, step by step reaching a point where they had lost that "inner peace" and security and totally lost themselves (I can say this only about the girls I personally know).
Sorry for the preaching I just wanted to try and clarify some misconceptions about why people have to wear the hijab. All what I am trying to say is that you cannot understand Hijab if you do not have that connection with God.
Also one little point I wanted to add is that Islam is not the first religion that commands the Hijab, original teachings of Christianity and Judaism also had the command of wearing a veil (worn only by nonnes nowadays), even some Hindus wear a vail as a sign of "modesty". I understand that people want to know why a girl would want to cover her beauty, but please do not (only) connect Islam with it.
If you have not turned Atheist yet I suggest that initially you do not talk to any other person about this except God, as it is a matter of faith. Ramadan is coming up in a few days inshAllah, pray that Allah makes easy for you whatever is best for you. I guarantee you that if you
truthfully ask God or Allah, or if you believe that there is any supreme being, you will find the answer soon. Good luck