TTC #2

So my husband and I have been trying to conceive baby #2 16 months now. I have had 4 miscarriages since then 😞 after countless doctor visits and a hysteroscopy I was told everything is completely normal. The doctor put me on metaformin because of my weight and a slightly elevated glucose (to was not pre diabetic yet). This month my doctor told that I should be highly fertile after the procedure. I decided to take opk to determine when I’m ovulating and turns out that I ovulated in day 21 of my cycle which was last Sunday. I took a pregnancy test yesterday because I am very impatient but it was bfn . Now I’m freaking out because glow changed by period day to Friday since i ovulated late and I’m terrified to get an bfn !!! I am losing all hope of every giving my daughter a baby sibling. And what makes it worse is she feels like it’s her fault we are not having another kid. She keeps telling me I promise I will be a good big sister, idk what else to do!!!! 😭