What should I do?

I havent had a period since April 14, 2014. My period always comes either the 14th or 16th of every month. Ive taken multiple at home pregnancy tests, went to the health department and taken some, and even had blood work done but everything is saying im not pregnant. Ive had pain around my appendex but the dr said that nothing was wrong. Ive been having to pee alot more often and i have and increased appetite. Not sure what to do. Any suggentions would help greatly.  Thank you!