I haven't had my period in 4 months now, not pregnant though because i haven't had sex since dec & i just took a pregnancy test at a clinic & im waiting on other tests on any stds i might or might not have thats causing it. what could be the reasons my pe

Many reasons: The clinic should have already told you possible causes, could be pregnant or problems with your female hormones you need the results of the blood and cultures and i recommend getting a pelvic ultrasound by a gyn doctor.

Many causes: STDs usually cause too much bleeding rather than delayed periods. Stress,weight, exercise, diet, medications, and diseases such as thyroid disease,diabetes/insulin resistance, PCOS, adrenal disorders, and pituitary problems can all cause you to miss periods. The clinic probably tested for all of these,and you should have your answer soon. Best wishes.