I can relate to a lot of what you are saying, and I felt a lot of similar feelings at your age.
Self destructive behaviours (self harm, suicide attempts) are something you need to speak to a doctor about. While in the short term it may alleviate some pain, as you're older and recovered, there's a chance you'll be asked about 'those scars' and have to explain, which isn't comfortable.
Transitioning young isn't easy, I'll be honest, especially with parents, but if you ask your friends to call you a new name, or he, many people that age are more accepting than parents, surprisingly.
Although, I do recommend speaking to your parents about your feelings. The earlier you get things moving, the faster your transition will go. If they aren't supportive, showing that you are persistent, consistent and insistent that you are not the female they think you are, they'll begin to see that it isn't a phase.
Personally, I found it easier to speak to my friends before my parents, because I found that daunting. Once I had the support of my friends, whom I could confide in should something go wrong (it didn't) I had the confidence to tell my parents.
As far as wondering whether or not you'll 'change your mind', that's only something you can answer. Many trans people continue to have doubts like that, but the fact you're thinking that doesn't mean you will, it means you're thinking carefully about your future, which isn't a bad thing.
If you are happier with a male name, under male pronouns and if you would like a 'male' body - it is likely that you are trans.
Again, it's up to you to think things through and to work things out, but myself and the people on the forums here are here for support and advice.