Maybe I'm not fertile?

My boyfriend & I have been having unprotected sex for the past year and a half. These last six months we've actually been TTC, and nothing. My periods are regular and normal so I'm just starting to believe I'm not able to have kids. Cuz there's no way I'm not pregnant yet, when we first started having sex and not trying we have sex everyday sometimes multiple times a day, so I feel like there's no way we missed my ovulation and fertile windows. I'm just so confused and don't know what to do, he gets disappointed and upset every month AF comes. So do I 😢 I got off of my period 6 days ago, and yesterday I started feeling super sick, headaches, nauseous, diarrhea, and being tired all the time, plus my whole body aches and is sore so idk. any tips or suggestions on helping my fertility or ovulation?