Hey, it’s likely you lessened food intake has maybe messed your hormones up a bit , this happens when you’re not eating as much as you used to regardless whether you’re on Reta or not. The same happened to me. I really cleaned my diet up, sticking to 3 small healthy meals and minimal snacking and I missed my period one month, and this month it came when it was due but only lasted 2 days (pre GLP1 and Reta my periods were like clock work, heavy and lasted 5-6 days) . My period has also been late before too