Hey mama, totally normal yan at 21 weeks! First time ko rin, parang gas lang talaga yung feeling ng movements initially, hindi immediately like those strong kicks you see sa movies, ang akin din ay parang light flutters or pitik-pitik lang, lalo na kung first pregnancy mo. Every mama and baby is different din, so kung konti pa lang galaw ni baby at hindi pa malakas, basta consistent siya even if sporadic, okay lang, pero if you're worried or notice na parang bumaba na ang frequency after a few weeks, mas safe na i-check with your OB just to ease your mind!