I can’t orgasm from penetration anymore

I lost my virginity to my boyfriend a few months ago and when we did it the second time a few days later, I orgasmed from it. That was the first time I had ever orgasmed from penetration. Then the next three or so times we did it I orgasmed every time. But ever since then, I haven’t been able to. We’ve tried all different positions and different strategies but nothing seems to work. It’s just so frustrating because we were making it happen before and it wasn’t even that hard to do.