Why Do I Feel Like This?

I’m almost 14. I’m a girl, and I should have a good life. I have a lovely boyfriend, lots of friends, my family life is fine, I’m not perfect, but fine with the way I look and feel. Some days, I get out of bed and think: it’s a good day. And all that day I feel really content and happy, I have fun, even if I’m not doing much. But some days, I wake up and don’t feel the same. I feel really low and depressed, and I sometimes cry for no reason whatsoever. If one off my friends is having an off day, I automatically think they hate me. Or if I say ‘iloveyouloads’ to my boyfriend, and he only says ‘loveyoutoo’ back, I automatically think HE hates me. And I ask him and ask him till we fall out. I’ve told him some of this, and he tries to be nice, but he doesn’t understand. I sometimes suddenly feel really hot, in a freezing cold room. Or really cold in a really hot room. I get sudden pains, or headaches. I recently haven’t been getting to sleep till 2 or 3 in the morning, although I settle down at about 10 or 11. One major thing is that I always feel like people are talking about me behind my back, saying mean things or just watching me. If my boyfriend/friend doesnt text/call me back literally 2 minutes after I’ve texted/called them, I automatically get this feeling they don’t like me. I only started feeling all this about 6 months ago, I haven’t told anyone, because I think they will laugh at me, and I’m not close to my parents really. I don’t know what to do. It’s stressing me out, I sometimes feel like I want to commit suicide and I was even going to once, but I didn’t have the guts to. It’s making me so upset, I’m beginning to lose my bubbly, outgoing personality, my friends and I don’t want to lose my boyfriend to. I try to keep myself positive on bad days, by listening to music, or thinking positive things, but it doesn’t really work. I feel like I’m dying inside. :’( I just want to know what’s wrong. Please help me.