Have you tried a body sock
https://www.amazon.com/Abilitations-Dynamic-Movement-BodySox-Large/dp/B0042SYWMI/ref=sr_1_3?ie=UTF8&qid=1468347105&sr=8-3&keywords=body+sock? My kids, SN and NT, loved it. If you're seeing an OT, the office should have at least one you can try.
We first tried it at the OT's office (they had several). The kids called it the 'starfish' - you can see why once they're in it. It was one of the absolutely best purchases we made. It worked wonders when they were getting out of control, especially around bedtime. Sometimes when they initially put it on, they would get even a little crazier and when that happened, we'd make them lay on the floor so no one got hurt. That craziness only lasted a minute or two and then blessed calmness. None of them liked a weighted blanket and the beanbag chair wasn't enough. My youngest initially refused to put it over his head - that was fine. It still really calmed him down.