Miscarriage reasons

[Chgnyc]

Long story here but I have just had my second miscarriage and am looking for answers.

I had one healthy boy at 35 - we had no problems conceiving  and no problems with the pregnancy.
Trying for number two has been a year long process. I miscarried naturally at 5 weeks nearly a year ago. I was told that was likely chromosomal and given my age (38) I opted to just go straight to ivf with pgd. My first round of ivf failed despite it being a perfectly good embryo with all the right chromosomes. My second round of ivf started a little badly as my hcg levels didn't double right away but after the second reading it started doubling and the pregnancy continued. At 7 weeks we were so excited and relieved to see the heartbeat.  But at 8 weeks 5 days it was gone. The baby had died the day we saw the heartbeat. Again this was a pgd tested healthy embryo. I passed the baby this morning and have sent it off for testing but I have so many unanswered questions.

Now I've had a natural miscarriage, a failed ivf/pgd implantation and a miscarriage with ivf/pgd I'm starting to think there's something wrong with my ability to carry another baby. What could it be? Any guidance would be hugely helpful. Nobody seems to have any answers...
Thank you!