Irregular periods and heavy flows, what is going on?

Women's health
1

I am 17, now. I think I got my first period at the age of 14 or 15. I have a few concerns about my cycle. My cycle in the last 5 months have been 34 days, 34 days, 32 days, 34 days and 33 days. Fairly regular no? But my period is now 4 days late and lasted from today 39 days. Now I am not pregnant I haven’t had sex before. My periods can have a heavy flow ( but I don’t know if it ranges from normal to abnormal), which i also heard is worrying, I don’t know what is going on? I guess I have had a very stressful few months but I don’t know