I don't know what to do. Diet or stress?

I reached my desired weight a year ago and my periods were normal and heavy.

Hello! How long did it take me to lose weight from 75 to 50 kg, I really noticed that my period was irregular every month by about 2 weeks, but it was just as heavy. I reached my desired weight in May 2025.

Since then I've been eating for maintenance, and everything was fine with my period until May 2026. Everything was normal, the menstruation, which was still heavy, seemed to be settling back down.

I went to college for 2 months (May and June) because I had to take exams and I didn't go home at all, plus I ate pretty much whatever I could find, sweets and frozen foods. (a lot of frozen fish, potatoes) without much home-cooked food. And since then, in May, I haven't had my period once. Neither in May nor in June. The weight mentained. Idk what to do.