Is this my twin boys moving?

This is my first pregnancy and I'm 19 weeks 1 day today with fraternal twin boys. I am unsure if what I'm feeling is movement from the babies. I've read everything that says flutters, erflies, twinges, etc. Mine feels nothing like that. You know how when you get really nervous and your stomach gets all in knots? That's how mine feels. I also occasionally feel a rolling type feeling in my stomach when I've been walking around for a while. Does this sound like it's the babies or am I just imagining things?