If there is any person on this planet who is capable of lying about miscarriages - or "fugue states", or alcoholism, or any other form of victimhood - it's Jack.
So please don't feel bad for doubting her. Yes doubting self-proclaimed victims usually does more harm than good, even if you have good reason to be suspicious. But that's not a reason to throw all logic to the wind, especially when she uses victimhood as nothing more than either a criticism-shield or flagrant attention-seeking ploys. This does deserve scrutiny even if we have to be careful about saying it.
So please don't feel guilty if you can't help but doubt her. She does harm herself to various types of victim with her behaviour.