I have missed my period for 3 months coming on four now. Ive taken 3 pregnancy tests and all are negative. I have had symptoms of pregnancy, although my results are negative. And I do not know what could be causing me to miss my period for so long. Any help?

How old are you? It may be menopause if you're older. Go see a doctor ASAP either way.

Medications can effect your cycle also your eating habbits have you changed them recently in those months have you been gaining weight or losing? You could also have a stomach condition that could make you feel pregnant even make you look bloated like you were pregnant I would see your doctor tell him/her they can take a blood test to be sure if your not you should be checked out