I really wish I had known about SPD when my older one was a toddler. Looking back at it, it all makes sense now of course.

Both my kids love their weighted blankets. They sleep under them every night. Definitely worth trying to wrap her in one during big meltdowns. Or even just a heavy comforter since she's only 2 and they recommend no more than 10% of body weight, I think. Or see if you can do joint compressions (not sure if she'd allow that).

Is she verbal? My older son said only a handful of words until he was 3. We did sign language with him from 12 to 32 months. I saw my nephew have complete meltdowns because SIL didn't know what he wanted or needed (he also didn't speak until 3, and seems to have SPD, but they won't acknowledge it). I signed with younger too, but he was speaking paragraphs by 2 yrs.

Do you have a routine with her? My older son still melts down if we veer too far from our regular routine and he's 11. Being consistent helps prevent meltdowns.