Mothers Helper/ Childcare Help

Hello! I am looking for a mothers helper/ babysitter to help me with my two girls, ages 12 months + 3 years. I primarily need help with the baby, as my older daughter goes to pre school during the week. I am Looking for someone to assist me Saturday afternoons, mostly with the baby. I am home with both of them on Saturday, but with different nap times and needs, I could use a hand! I will either be home as well, out with my 3-year-old, or we can all go and do activities together. I would also like to set up one morning a week where I can get out to go to yoga for a couple of hours. We would prefer a nanny who has their own car, who does not smoke, who is comfortable with pets, who is CPR certified.