Work is making me come back full time

Just need to vent...

I told my boss this past January that I was pregnant and wanted to switch to part-time when I return from maternity leave. At that time she said we would have to see how the caseload was (I work in outpatient therapy).

A few months later it was verbally confirmed and they hired someone to cover my maternity leave and then would work between two locations when I return.

About 6 weeks ago I confirmed my part time return via email. I would start out “full time” status but work my 3 day schedule and then we would do the paperwork my first week to switch to part time. Ok great!

3 weeks ago my boss calls seeing if I could temporarily work more because we were so busy. She also explained that when I returned, they would be hiring an additional full timer because we were getting busier. I did agree to helping a few extra days in the meantime.

Now today, just 5 days before my return, I get a call from my boss stating that admin has denied me switching to part time and that I have to return full time.

FMLA guarantees your prior position, but I have emails stating that I am good to go for switching to part time. I have been crying on and off since this morning. This is the absolute worst case scenario and I don’t know what to do.