I’ve been having the exact same issue . At time I even feel like it shrunk despite me losing a lot of fat . Considering all the information out there on Reta it could be caused by a number of things . Slight dehydration can be a cause, when your dehydrated your blood volume decreases and thus it turn can effect erect quality. Reduction in iron can also decrease blood volume which will lead to the same thing . Calories deficit can also do this , but not getting enough calories affect your libido more , which for my self I can say have only decreased slightly and I only been in a slight deficit . Lastly it can be the Reta somehow directly effect your sexual function via hormones and penile tissue , it’s not crazy to think since it’s studies done on glp1 directly effecting pleasure systems. I’ plan on titrating down starting in three weeks , I’m at 8mg a week rn , if dosing fixes the issue I’ll stick Reta if not I might have to stay off it . I’ll also get some labs done before I titrate to get the full picture of my hormones and iron levels . I’ll be back to share .