Definitely talk to the Judge about the possibility of doing community service in exchange for paying the fines. Though I do know that there are some fees that cannot be waived, so you would still probably have to come up with some money, or be at risk of going to jail.
First off, you should be paying your own fines! You got in trouble, not her. Second, go mom! Third, they can revoke your probation for not paying your fines. In some situations, if it is revoked then you will have to do your original sentence the judge set out for you to do before he/she placed you on probation.