Why is it taking so long TTC after I miscarried?

Okay so a few years ago when me and my boyfriend (now my fiancé) wasn't trying to get pregnant, I got pregnant, but unfortunately I had a miscarriage at 8 weeks. He told everyone in his family that I was pregnant and then I miscarried. I didn't tell anyone I was pregnant so my family never knew. Now that we are engaged and are actually TTC, it's taking forever! I'm stressed out and aggravated. When I wasn't trying, and we weren't really "ready" financially or emotionally to be parents, it happened. Now that we are more stable and actually want a baby, I get disappointed every single month. It's like my body is backwards.  Is anyone else in this situation? Why is this happening to me? I just want us to be parents.