My boss is harassing me about work!

I'm taking the bare minimum off of work, going back at six weeks...I have an appt on Wednesday and am going to work that night. And she won't stop calling me to try and get an earlier appt to work a 12 on Sunday, Monday and Tuesday. 😠 I told her that my dr isn't available before my appt and I can't see another dr because the one who put me on leave has to be the one who clears me. And she's not getting it. Keeps telling me to keep trying. They've been short staffed, and I get they need me back...but damn. I'm already taking as little time as possible off! Give me my last few days! It's not my fault they won't hire someone else to cover the days I'm not available! Now she's pissed at me telling me I need to call and fix the schedule immediately...after telling her I was at the hospital visiting my grandpa after surgery. How about, don't try and schedule me before being cleared to come back to work? I'm about ready to take my additional 6 weeks of leave because she's irritating me so much...