It may well be that ADHD is part of the picture, but it wouldn't explain everything. The pre-school program is a good idea - don't let it throw you that he wasn't interacting. That would come with time. If you can still enroll him, it would probably help. Relative to therapy, it's not surprising that face-to-face sessions for him were not useful. The chief value of professional intervention for many very young children is the collaboration and planning that can occur between the clinician and the parents. Another evaluation would be in order, mostly to achieve an accurate diagnosis so that proper intervention can occur.
first of all a child pshycologist should not try to get your child to talk they have certain technices like wathch them play and have them draw pictures. i know because my nephew has been through it. and yes it kinda does sound like adhd my nephew also has that.
Just another thought, although your child is young, would be to consider tourette's or similar. My friend's son's behavior was similar as a young child, where he developed vocal tics and OC traits. Especially if there is a possible family history. Her brother also had tourette's - his symptoms cleared up after puberty.