Ive had my period off and on for almost a month

Hi, ive been having my period off and on for almost a month. I dont know whats wrong with me. I dont actually flow, its more like spotting. I wear a pad everyday because i never know when im gna need it. Some days theres something there and then some days nothing at all. It ranges from brown to light pink when i wipe to actual menstrual blood flow which is light and only last a couple hours if that. Before all of it started, i was a month and a half late. I noticed when i really 'bled' was after sex or masturbation. The rest of the time i can go a day or so without anything. Im really worried, i dont know whats wrong or what to do. Please reply. I need some advice.