Have you invested so much in this struggle that it is now about power and not the potty? Does your reaction to wetness give your daughter attention she seeks but does not receive otherwise?

Sorry to be so blunt, but those are the two impressions I get from your post.

With my son, whose SPD was not then diagnosed, the adults had to get completely it of the issue and let him work out the whole process (after he'd been shown/instructed/seen video's a hundred times) for himself, because that's the way he learns. In the end I offered him a bribe - a toy he wanted - and told him to let me know when he'd managed to be dry for a certain number of days and he could have training pants until then. Other than that, I shut up and ignored the issue. He was 4+ when he managed it, but once I gave ownership of the issue to him, both of us were a lot less stressed.