Why can’t I get pregnant?! 😭😭

Lupita

So my husband have been trying to conceive for 4 years and no luck and when I got my first positive last year in May then I had a miscarriage at 6 weeks and since then we have been trying again but no luck at all. Every month I get period it’s so devastating especially this month it hit me the most that we tried on my fertile days but today I already feel my usual period back cramps so I’m sure I’m not pregnant and so I been so emotional today and I ask myself why can’t I get pregnant and have my baby with my husband which I feel it’s so unfair, I dint understand.. any helpful tips I should do differently to get pregnant around my cycle? I have attached my cycle with my fertile days for any recommendations..