Look, I don't know TBH.

DD1 was especially tantrumy and difficult between 2.5 and 3.5 (but for a lot of time she was housebound as I couldn't walk with SPD). She was having major meltdowns about every hour. But apart from that, I can't remember anything that you describe.

She's 4.5 so a bit older than your DD now but MOST of the bad behaviour has gone. Sure she still has her tanties but it's usually over something I understand would make a child tanty not something really silly.

It sounds like this is causing you and your family some angst and I think on that basis alone, it's worth checking out. It might be completely normal and from what others have said, it could well be. But if I had questions in my mind and it was happening a lot every day and showed no signs of abating, for the sake of $300 I'd check, even just for peace of mind. If there is something wrong, the earlier you get on to it the better. You could do nothing, post again when she's 4.5 if there's been no progress and kick yourself you hadn't done something earlier.