Sparkling a similar thing happened to me when I was pregnant with DS.
I had a massive bump, so big that a woman having twins felt sorry for me when we were chatting at the doctors one day, and I was just getting into a fairly crowded lift when a man came rushing up being me and pushed me forward saying "come on love, move up, make some room!"
Only there was no room, because even though the lift was massive, it was full of giant Ikea trolleys, flatpack stuff, and my stomach, which was developing it's own gravitational pull by that point. Small things would orbit me if I got too close to them.
He actually pushed me bump first into some big flatpack thing someone else was buying, and then DH said "if you push my pregnant wife one more time I'll rip your arm off" and the lift went very, very quiet.
I was like you though, too shocked to speak, but regardless of baby bump, how dare he think he could just grab someone and push them? He didn't push DH or the man at the other side of me, so I think it was just he felt he had a right to put his hands on a small woman and move her out of his way.
That was a bad trip to Ikea though. Later on as I waddled slowly to one of those stock check screen things a girl of about nine or ten ran up and banging into me, trying to beat me to it I think.
She came from behind and off to the right of me, and she reached it a split second after me, which was the first time I was aware of her even being there.
She ran off again and came back with some whopping great teenage boy about a foot taller than me, and then a woman came after them, also taller than me, with the girl telling them I'd pushed her out of the way, and they all stood really close to me to intimidate me into moving.
I was at that bit of the pregnancy where everything upset me, so I waddled away again and sat on a bench and cried until DH found me, then felt too daft to tell him I'd been picked on by a little girl.