I would bring it up to the family probably before the mothers maternity leave. With your degree you could possibly making more money doing something else. You have been with the family for a while and I am sure they are appreciative of having you around. If you will be... more
You should be getting paid by the hour, so you should be getting paid for working overtime.
Care providers charge anywhere from 15-30 an hour for children with special needs. You can include your volunteer work in your experience, if you have a point of contact that would reference you.