Irregular period

Eleanor
Hi all,
​I am currently 16. I've been having periods since I was 10, and they've always been very regular. However, in the last year or so they've gotten very irregular (anywhere from 25-35 days) and I don't know what to do. Also, sometimes they're extremely heavy and long, others short and light. Should I talk to my doctor about BC? Or is there something else I can do?
​All help is appreciated!