Should I be worried?

So I got my period when I was in 8th grade. I’m now getting ready to go into my senior year of high school. At first my period was really regular about every 28 days or so for about 6 days. As time went on it started to not come as often. Now I get it anywhere between 30-57 days for about 6 days. I’m worried that something is wrong because I’ve always been talk it should be anywhere from 28-30 days for 5-7 days. Is this normal? Should I go to the doctor?