hi and welcome to arachnoboards. If im not mistaken a pregnant female will refuse food. Also, if you expose her to some light you may be able to see some scorpion embryos through her membrane. And she would also be more agressive than usual.
It may be what's wrong with mine... I bought it about a week ago and it seemed fine, then a few days ago it developed the bulge. It's eating and seems fine though. I'll just have to wait and see I guess.