Why is so hard yo get pregnant naturally?

Why is so hard yo get pregnant naturally? I try and try and try and every month is so sad to not even have the chance to take a pregnancy test. This morning I heard two ladys saying that one of them just got pregnant and the other one was a few months pregnant now. I got sad of course.

I have a daughter, this pregnancy was through IVF.

I always ask God why is not happening to me 😭