Can anyone further along/second time mamas tell me what those first flutters felt like?

I'm pretty good at working out what's a gas bubble, a muscle twitch, or my own heartbeat (which has got me excited but then I've realised it's my heart, not the baby's haha, so that throws me off a bit sometimes)... but I keep having these little, pulls? Flicks? Pumps? inside me around where my uterus is that I just can't identify. They're super slight and are gone in an instant, and I don't know if it's too early- 16 weeks tomorrow.

Can anyone describe how those early movements felt?