Oh hun, I'm so sorry. My heart goes out to you. I constantly have issues with my mom, because no matter what I try to do, she always ends up yelling at me, or slappin me. I'll try to explain something, and she'll think I'm trying to be rude/disrespectful/disobedient. I know how much it can hurt, even though I'm 3 years younger than you. You are NOT a bad person, they just don't understand you. And about the period thing, don't worry about it. I was the youngest in my family (within the past three generations) when I first got my period, and everyone else was around 17 to even 19 when they first started. everyone is different. I know that the fam. can be a pain. even if you dont think you need to, try to explain to them what you piont of view is(in a way that has been reviewed by someone to make sure its not taken the wrong way) and ask them if they can forgive you. You are a wonderful person, therefor you deserve to be treadted wonderfully. ^_^
Warm wishes,
-Vicious