Quoting dream:" without a specific example, I can't give you a specific answer, but I noticed that you emphsized consistency. ... [snip!] ... to tell you something but didn't know how? Don't try to fix the tantrum. Focus on finding the issue before the tantrum starts."
I think a big part of it is trying to tell me something but I don't understand. The speech therapist has also made a good point about trying to "force" her to talk, not in a cruel way, just don't always immediately give her what she wants. Make her work for it, give us some sort of verbal clue, not just pointing and signing. And I think that's setting her off a bit, too, that we're not just giving in to it.
Sometimes, it's that we won't let her walk around in the grocery store, because she's still not that great about holding hands, and listening to us (like don't run away, don't grab things off the shelf, etc.). Or that we won't give her a popsicle until she's had real food. Some things we can compromise on, sure, but it's still that she almost always goes to a tantrum as her backup. Like that will get her what she wants. And we rarely ever give in to it. Most of the time, when she starts flailing about, we do put her in her room, or on the couch, or even in the middle of the floor to let her finish it out, and then we try again.
By the time she's in the tantrum, we can't pull her out of it. And we try talking calmly and distraction, and cooperation in some cases before she reaches that point, but it's just not successful