I don’t remember when I reached puberty, so I do not know when fasting became obligatory upon me or whether I was already fasting at that time. I also was not praying then, and during some of those fasts I watched haram content. Do I have to make up the fasts from the period when I was not praying?

Ustadh AbdulAziz al-Haqqan

We do not build rulings on assumptions. You have to know that if this happened after you hit puberty, then you make them up. If they didn't happen after hitting puberty, then there is nothing on you.