I used to have tantrums as a young child, but my parents weren't the sort to tolerate that kind of thing at all, they seemed to see it as a challenge to their control, so I guess I must have had it knocked out of me, if it was ever really there. I don't know that the tantrums were any more severe than an NT child would have thrown, and I don't remember feeling traumatised at being forced to compose myself.
I've only had one episode since those very early years, that could have been called a meltdown, when I was in my 20s. I was in a very difficult situation with a partner, under a lot of pressure. I thought I was going to laugh, but my breathing went out of control, hyperventilating. Seems like a panic attack, which I guess is a kind of meltdown.
Beyond that, nothing. I'm an unusually calm, stable person. I sometimes get quite ruffled on the inside, and I feel my fair share of anxiety and hopelessness, but from the outside I continue to behave quite normally.