Ay sis, totally normal yan! A few of us moms din ganyan sa 20 weeks, lalo na kung first time mo, sometimes ang baby movements ay super subtle pa, parang butterflies or gas lang kaya madaling mamiss, especially kung busy ka or concentrated sa something. Marami akong kaibigan na super minimal ang ramdam nila sa early weeks tapos biglaan lang umusbong, so don't worry yet, pero if you're really concerned or by next check-up walang changes pa, best to mention it sa OB mo para ma-check ang baby's position at heartbeat.