I never felt flutters mine felt more like little mucle spasms and usually in the same spot to begin with around 16 weeks i think but as time went on there was no mistaking movements. I'd describe them as little taps on the inside getting closer to the 20 week mark and now at almost 28 weeks boy oh boy your belly pokes out in areas where the baby moves and tummy jiggles and you can see it move like a wave.
I could never figure out what I was feeling either. Flutters or gas. I began to feel more distinct movements around 19 weeks. It sort of felt like something brushing up against me. It got stronger and stronger and now there is no doubt what I feel..he's beating me up inside...lol.
So, you are almost 16wks...Usually quickening happens anywhere from 16wks on. It feels like tiny tapping, or very subtle pops...it will become more obvious to distinguish between quickening and gas as it occurs. It's one of the best parts of being pregnant, have fun!!
I started with a faint popping inside, as if a small bubble popped. I had dismissed this feeling thinking it was due to gas only, then I realized that it often was in the same spot. As the days went by they became distinctive and more regular, so I understood that it was the baby. My little one is clearly not a butterfly either, but he knows how to make bubbles.