Why can't I eat, sleep, think, concentrate, study, and why do I keep forgetting things?

I'm an 17 year old girl, I ALWAYS eat healthy, exercise and get good grades but I haven't been able to sleep, concentrate, eat, study, exercise, or do pretty much anything for the past 2 years. I'm always forgetting things. I was bullied for 12 years and since I've graduated high school I haven't been able to do anything the way I used to. I force myself to eat, my parents always yell and lecture me about the things I'm doing. They think I'm anorexic or bulimic because I just don't feel hungry but I always force myself to eat because I know I need to. I barely get any sleep. I always have nightmares even when I do get some sleep. I can't concentrate on anything. I space out, forget to do things. I can't study at all, I stared at my books and computer for 18 hours yesterday trying to get myself to study. I can't think straight. I'm always tired. I don't feel like exercising. I went from being what my normal weight has always been: 118 Ibs. to 145 Ibs and it doesn't even look like I gained weight at all. I've never done drugs, alcohol, smoked, or anything like that and never will. I just don't feel like doing anything. I feel like everyone and everything is against me. I'm always tired. I'm angry at myself all the time now because I can't do anything I used to, it feels and looks like everything I worked so hard for is falling apart and it's all my fault. I literally lay in bed for hours trying to sleep, and drag myself out of bed everyday when I have to get up. My body is always sore, and in pain. I graduated high school a month after turning 15. I'm in university right now and nothing is going the way I want it to. I can't concentrate, or do anything. I try to learn but my mind and body literally shut down on me. I sit in the class trying to listen to the lectures and take notes, but after someone nudges me about class being over I realize that I couldn't hear anything that was said, and didn't have any notes at all. I'm always spacing out. It took my sister 48 minutes to snap me out of my spacing out yesterday. I'm so sick of this, and no this is not about any relationship. I'm the girl whose always cared about her education and future, there has never been anyone who is not family or friends in my life, and there won't be until I finish school. I had to cancel all my extra-curriculars because I just don't have the energy, patience, concentration that I need to participate in them. I'm confused all the time. I don't know what to do. My parents have taken me to every doctor and psychologist in my city and they are all idiots-and that's putting it nicely. I seriously can't take this anymore. I feel the need to scream all the time just to get everything out.I forced myself to exercise to blow off some steam but it didn't work. No matter how hard I try and work, everything proves to be useless. My straight A+s have been turned into Straight Ds. I can't take it. Please help me, any helpful advice, suggestions, comments, would be appreciated, thank you in advance, and I'm sorry for making you read this long explanation.