That's grand, if you can get her fixed for free, stress the Pit Bull
Glad you've got some money coming in of your own, does help with the parentals, they cannot use 'money' as a reason not to keep her!
Sounds like they cover quite a bit in the States. We don't have the rabies shots, unless the dogs going over seas, but we pay $350.00 just for the de-sexing, never mind anything else!
Last resort if she does come into heat before being de-sexed (it can happen with all the best laid plans) immediately get the 'doggy contraceptive pill' - it works but doesn't keep the wanna be suitors away though - wish they'd find one that did!
That's grand your Mom's taken to her! Stay positive, keep working with her, she's your girl!
I'll send some positive thoughts your way too!