Working while pregnant

How's everyone's experiences working while pregnant? I've had an awful week. After a mc in may I am now 11 weeks pregnant and I am back to work. I am a teacher.

This week has been awful, my boss knows I am pregnant but the pressures on me already are massive. I work with 3-5year olds so I'm up and down and moving and never off my feet. I also work with additional needs so some days are very challenging. I guess I'm just worried 3 days in and I'm stressed up to my eyeballs! And I still have at least 5 months left in work! Aaaah!