Period help.

Hey guys. I don’t know if it matters but I’m 18 yo, 5’5 and weigh 115lbs. I am usually pretty regular on my period but a couple months ago my period was two weeks late and lighter than usual. I took tests and I was not pregnant. I then got my full regular period two weeks later. The next 3 months my period was normal with no problems. This month it is 3 days early and lighter than usual again. I had sex with my boyfriend one month ago while on my period with a condom. I haven’t had any weight change or symptoms of pregnancy. Any thoughts? I know pregnancy is always an option and I still have not taken a test but I was hoping someone could tell me other things that could be going on besides pregnancy.