Hi I'm 34 Years Old And Nit Had A Period

Hi I'm 34 years old and nit had a period since april i am 5'3 and 14 stone 9 i have put a few pounds on recently i get a bit of backache and am tired quite alot and now im having a bit of pain after urinating i did take a pregnancy test at the begining of may which was negative but could i be pregnant if not whats wrong with me thanks