Aw, totally normal yan mama, si baby ko rin dati ganyan, lalo na at 20 weeks pa lang, so movements can be really inconsistent pa talaga! One of my mum friends told me na it depends on baby's sleep cycle, kung anong position ka, kung gaano ka-active, sometimes even kung kumain ka ng matamis, so hindi every moment equally active si baby. The thing is, at 20 weeks you're just starting to feel movements consistently, so iba-iba talaga ang pattern for a few weeks pa, wala pang solid routine si baby. But since this is your first pregnancy and you're already worried (which is super valid!), best to give your OB a quick call lang to put your mind at ease, they can check at the next appointment or sooner if kailangan, then you won't be stressed the whole time. I remember I called mine din just to confirm lahat okay, kasi peace of mind is priceless talaga when you're expecting!