Negative pregnancy

My first time writing a post but I'm so lost for words. My husband and I have been TTC for almost 3 months we both are 25 and 28. I exercise at least 5x times a week and I eat healthy, I also take prenatal vitamins everyday. I follow my fertility window and when I ovulate and still have negativity pregnancy test. Can someone please help me, I don't know what else I am suppose to do. Please