Progesterone pills effect on bbt

My dr started me on 100 mg prometrium (progesterone) at bedtime on cd 11 due to my heavy bleeding. She did an ultrasound and discovered that my uterine lining was way too thick. During the ultrasound she saw a follicle growing on my ovary and thought I was going to ovulate sometime soon but not immediately. I dont think I ovulated yet and its the progesterone that's affecting my chart and making it look like I have. She told me to take 200 mg if bleeding starts to get heavier, which i have the last two nights. Anyone experienced this? Am I correct to assume I have not ovulated? I have done opks and they are all negative.