Cycle changes

My period has always been pretty normal/ regular. It usually varies from 26-30 days. But for the past two months, my periods have been kind of weird. On November, I had a normal period, but it was a little lighter than normal (I still had a heavy day w/ clots and all). December, my period was late by 5 days, which is kind of unusual. But it was pretty normal. Now January, and I can already tell my period is going to be late again. (I’m already a day late). pregnancy is out of the question due to the fact that I haven’t gotten ANY in the past 4-5 months lol any thoughts?