Why do i feel like my heart or chest tightens whenever i am upset? i couldn't sleep very well but i am somehow very exhausted, lost my appetite in eating and i feel restricted by everything i do. they say i'm pretending to be depressed and that hurt?

Some peoples system reacts like that to stress. But you can change that with gradual modifying your behavior yourself by taking deep breaths at the time, learning how to meditate and other such means. Other way is to take a tranquilizer under care of your MD. The first is better for you become under your own control and there are no bad side effects. you can do it! Good luck.