I think a "normal" cycle is anything in the range of 21 and 35 days. So your pattern looks pretty normal. I suppose if you had big jumps from 21 days to 35 days fairly frequently that would be irregular too. I was always 22 days spot on until I was about 30, then I moved to 24 days everytime until I was about 40, then 26 days until I was 45, then it went completely random sometimes 15 days on followed by 15 days off, sometimes 30 days followed by 10 days on, then 18 days. My last period was 6 weeks long before the docs intervened. Now I don't have that worry anymore