why is it difficult to get pregnant?

Hi There. Why is it difficult to get pregnant? I'm trying to conceive for atleast a month. I've always using an app just to tract my fertility window. I know i'm ovulating nman and every month na kpag naghihintay ako lagi akong may pregnancy symptoms but it always turned out to false pregnancy. Laging failed ayoko ng umasa sa symptoms ng implantation bleeding na yan kasi the most reliable nman tlga is missed period. I'm sorry for my post disappointed lang tlga ako kasi laging unsucssessful. Nkakalungkot lang tlga rang ayoko ng umasa???