Upset with rude boss

I've had complications with my pregnancy and am at a point where I have weekly doctor appointments to deal with gestational diabetes and fetal development issues. My boss complains that I'm missing too much work and pushed for me to go on maternity leave now.  I got very upset because I know she can't force me to leave.  I suspect a co-worker complained to her about my absences. Any advice?  I talked a lawyer who confirmed my boss can't force me to leave early.