I've said it once and I'll say it again - NOBODY KNOWS IF THEY CAN GET PREGNANT UNTIL THEY TRY. Even if you've already had one healthy pregnancy, there's no guarantee that subsequent ones will be the same. Miscarriage is horrific. I can only imagine what she went through at 19. But they often happen for absolutely no reason and through no fault of the mother.
I agree 100% you should look after yourself as best you can before trying (especially stress wise). But if she really did have a long list of ailments wouldn't she have a corresponding list of specialists she has seen
if she's earning 6 figures she could have top tier health insurance. Even if she doesn't she can pay to see a specific consultant she wants regularly (I have done this). But no, she'd rather deflect and blame her GP (he's not a specialist). As someone with chronic illnesses, she's as transparent as cling film.
She reads things online and claims them as hers. It's all exaggerated. No doubt she has had tummy trouble and iffy periods. Like most of the population. But that doesn't sound as good does it