Needing some support/advice

So..first time “mom” here. I’ve had five miscarriages, (four from previous relationships one from current) and I’m not sure what I am doing wrong. I have recently been diagnosed with POTS, I have a small aneurysm on my aorta right above my heart, and I have a heart condition (won’t go into to much detail so it’s not a long post) but could those be reasons why I keep miscarrying? I also haven’t been able to get ahold of any prenatal vitamins during those times could that also be the reason? And if there are any good/cheap prenatal options I could go for please lmk! I’m just feel so drained and like a failure as a mom and a woman. My s/o has been so supportive but I know it’s hard for him to because he’s been so excited