Irregular Menstrual Cycles with Endometriosis

I've heard endometriosis can cause irregular cycles, until recently I never experienced this? My past couple of cycles have been very off? Went from 31 days with 3 days bleed, to 23 days and 3 days bleed, to 29 days and 2 days bleed? Before that I've always been between 25-27 days cycle and 5 bleed days? Any ideas? My doctor says it's still in normal range so it's fine? But it's not my normal..