Babysitter Needed for my Children - Full-time / Part-time

We are looking for a great babysitter for 3 children in Cambridge. We would prefer a babysitter who has their own car and who does not smoke. I work in a group home and my husband is a laborer so his hours vary by job. I have a set schedule but sometimes am asked to come in and work doubles and I have 1 manitory meeting a month which hours vary for but would get 2-3 week notice for.