IRREGULAR PERIODS?

OKAY IVE HAD IRREGULAR PERIODS ALL MY LIFE WHICH IS ODD TO ME. I STARTED MY CYCLE WHEN I WAS 12 YEARS OLD, IM 26 NOW!! MY OBGYN SAYS THERE'S NO PROBLEMS WITH ME, NO CERVICAL ISSUES OR CANCER OR ANYTHING. BUT I THINK OTHERWISE, SOMETHING HAS TO BE WRONG. I WAS A WHOLE 33 DAYS LATE ON MY PERIOD, WITH A NEGATIVE pregnancy test, THEN ALL OF A SUDDEN MY PERIOD COMES ON AND HAS BEEN ON 8 DAYS NOW. NO CLOTS, NO CRAMPING, HEAVY BUT NOT SUPER HEAVY. THIS IS SO ANNOYING. I NEED SOME REAL ANSWERS NOT SURE IF I'LL GET IT HERE 🙄🙄