Please explain what these synptoms mean?

I have been paranoid before, lip biting, jumpy, (even if I hear someone coming or they tell me I jump or scream when they come up behind me). Recently it's been getting worse, I've been clumsy, I can't have doors open, I hear and see things, (noises and things moving in the corner of my eye) I'm terrified of the dark and I shake. Worst, I always feel like someones watching me, so breathing feels like there's someone pushing lightly on my chest and I feel like I have to look everywhere at once. When I try to hold a conversation my words get flubbed and sometimes I feel like I'm not in reality and that nothing is real. It's starting to scare me and I think it's more serious than I thought. I'm 15 and female if it makes a difference. Please have references when you answer, answers without references will be disregarded.