Long cycles, is it something serious?

Stacey

Im 17 years old & I have used the app flo for months now but just recently started using this app as well so I use both anyways flo lets me see my cycle days, it usually passes the 35 day mark is that normal ? Im scared I could be infertile I dont even knoooww.. I get my period every month lasts 7 days heavy flow for 3 days but changing pad about every 4-5 hours is good for me, should I speak to my doctor about this ?