Oo mama, yan na yung baby mo! Those bubbles and flutters at 20 weeks are definitely fetal movements, that's the sweet spot when FTMs start feeling baby for real, and some of us describe it as popcorn or butterflies, so you're experiencing exactly what we all go through. The quick movements you're noticing are totally normal too, babies move fast at this stage, kaya sometimes nakakagulat talaga! I'd say keep enjoying these moments and monitor if the pattern stays consistent, pero puwede mo ring i-mention sa next prenatal check-up just to be sure everything's progressing well with baby.