Kumquat came to my ultrasounds of the twins; DH kept him (relatively) quiet and contained. He was too young to know what was going on.
By 24 weeks, it was dangerous for me to walk or drive alone, thanks to the extreme dizziness.
It really was a horrible pregnancy.
OP, I wouldn't bother telling her when your ultrasound is, even after you have it. If she asks you about it afterwards, you can cheerfully say, "oh, I already had it done."
Friend: But we were supposed to come! I promised my daughter she could!
OP: It wasn't your decision. Bean dip?