Does anyone have a recommendation for a psychologist who can provide an assessment (ideally more than just an IQ test) near the Fairfield County area that is experienced with working with very young children?

What kind of assessment are you looking for? If you suspect a disability, the most straightforward way to go is to inquire with Early Intervention and/or your local public school special education department (depending on the exact distance from 2.5), both agencies which assess many very young children.