I know how overwhelming this is and how this may seem like a set back but, from your post, it doesn't really sound that bad. Even NT kids find a new school unsettling and take a while to warm up to it - especially when it's K and when it's large group! Two of my kids have ADHD and some sensory processing challenges and they still have challenges in the large settings. Until they're comfortable in their surroundings, they're also a lot less verbal (which common across all populations). As far as the aide goes, are they expecting you to pay for it or will they provide it. If they provide it, I would absolutely take them up on it. Hang in there!