My period didnt come in may, then it came on the fifth in june and now it didnt come this month yet.my pregnancy tests were negative. is this pms?

No: Its possible that you aren't ovulating. When you aren't ovulating you tend to have random periods. If this is a persistent problem, you should see an Ob/Gyn about it and find out why. PMS (pre-menstrual syndrome) is something different. It is moodiness, irritability, bloating and other symptoms that happen during the week prior to your period). Best wishes!