Trouble with work

I am 27 weeks with my second , Im a preschool teacher and on my feet, bending, getting up and down, changing diapers, all day long. Regardless Work is a long day physically and mentally! I have been in a lot of pain this time around for weeks; lighting crotch 😖 back pain and light spotting. By the end of the day my legs feel like they’re going to snap off! Yesterday was a really rough day for me and I didn’t sleep much last night because of it. So I messaged my boss that I needed to take the day off to rest and explained why. She is trying to guilt trip me and make me feel bad because we are short staffed and just had two other pregnant girls go on maternity leave. Anyone else dealing with something similar??? I need to take care of myself and baby! I rarely ever miss work and if I do it’s because my son is sick. I’m only human 😭 I want to work until June like planned but I’m feeling as though my boss is going to make that very difficult for me. Sorry I need to vent! She just really put me over the edge