I can't poop AT ALL.?

I've tried pretty much everything. (I've tried diet tea. It works, but I don't want to be drinking that crap all day.) Laxatives, I haven't tried because I heard that they're bad for you. I've sat on the toilet for literally 2 hours, and nothing has came out. I eat a lot of fiber, NOTHING. I go to the doctors, and he prescribes me this powdery sort of laxative, that's healthy for you I'm uming. NOTHING!! What the hell do I do?! I've had this situation for about 1-2 years now. Maybe even 3 years that this has happened. I can't take it anymore, I don't want to keep drinking dietary tea all day!!!