We live off Marsh and Keller Springs, too! Our son stayed with an in-home sitter from six weeks old to three years! (Then we moved him into a preschool). The woman is AMAZING; has kept most of her kids from infancy, too, and is full of love for them all. She has all her certifications and licensing, does real "curriculum" with them (and every child she's kept is super smart, and ahead of their development age!!)
Message me if you want her contact information; it would be a great place for your child! I do know she accepts part-time like you mention (2-3 days a week), as well as drop-ins for a few hours, and she has worked with families on different rates according to their situations, so I'm sure she'd do the same for you. Good luck!! :)