Advice on boss

I’m 30 weeks pregnant and I’m in rough shape, I have swollen veins up and down my leg and they hurt so bad! Not only that but my legs are swelling! I’m a waitress and I recently said I can’t keep doing the 13-14 hour shifts. I’ve also told a co worker who was looking for shifts that when I go in to push out this baby I will have shifts I need covered. Here’s where I’m getting mad, that co worker told my boss she quit her other job and was trying to pick up shifts when my boss told her I’m not due until August (I’m due in July) why do I need off now? And when a separate co worker told her she was off on a Saturday my boss responded by asking if she was pregnant too. I don’t get paid maternity leave and we have a permanent schedule so if I want to go on a month long vacation(or taking off to have a baby) as long as my shifts are covered I can do that. Why should it matter why I’d like to stop working if my shifts are covered and why is she making comments to other employees about me. I also wasn’t planning on being done until 36 weeks. On top of that I told her they are watching me for preeclampsia and my heart rate was over 100, Im anemic and I failed my glucose screening. My boss says I’m fine and I failed my glucose because all I eat is sugar (not true, I am just a pickier eater) Am I overreacting for being upset? I don’t even want to go in and deal with her. Any advice on how to approach her?