What wrong with me!?

Hello everyone!! It’s been a long time sense tha last post about my marriage to my wonderful husband. BUT! I have a really big concern. During my last relationship with my sons father it was really easy for me to get pregnant (even though it wasn’t planned) A drunks night story💀. Anyway! I found out really early, like the first day of my missed period I was pregnant. My lifestyle, such as foods i eat and things I drink, workouts etc. are the same as it was before I got pregnant, but for some reason me and my now husband can’t seem to get pregnant. We have tried manyyyyy of times and even planned on the days I ovulate but still nothing has come to positive and all my periods are still regular. 😭 I feel bad because although my husband loves his stepson Ik he wants a child of his very own. Please

helpp!! What can I do?!