I'm sorry you're having trouble with the $$$ part of being a BM. It's probably helpful for the current/future brides to hear about your situation as a reminder on how to treat their girls.
Being a BM is such an honor but when accepting remember all the responsibility financial and supporting that goes with it.
In the long run, you'll have the money and I'm sure you'll be glad you were part of her big day. Hang in there and just because the other BM's have jobs, they may be having $$ problems of their own. (for some, the more you make, the more you spend.)