Did you get anything in writing (email)?
You could ask your obgyn primary to do a medical letter regarding your need for more time. It might fall under mental health but its another option to be able to be approved
This is where talking with your employer is best. I'm no legal/hr expert but my understanding of FMLA is that its ultimate goal is to provide job security (i.e. makes it illegal to fire you for covered reasons while you are out). FMLA provides up to 12 weeks of UNPAID job protection and time off. You qualify for this federal protection only if you meet certain qualifications (e.g. minimum hours/time employed). There are additional provisions that are state/employer dependent that can add to this protection. The Virginia Personnel Act provides up to 8weeks of paid time to child bond with your newborn (or foster/adoptive) child within the first 6months of birth or placement. This also requires you to be elligible for FMLA if you want this added PAID benefit.
Hmm... given how new PWFA is, your employer may be the one that will have to work with the agency for your case. I found this article that suggests your employer should be able to give you accommodations that's potentially up to 40w? https://www.jacksonlewis.com/insights/pregnancy-accommodations-and-pwfas-final-regulations-your-questions-answered-0
Talk to your principal. They might be able to approve more time off without pay even if you are not approved by HR.
I have no advice/info, but that is so frustrating! I’m sorry mama.