Pregnancy Weight Gain

Hi mga mamsh, so eto nga po 34 weeks in nako based on ny LMP nd previous check ups and scans. I was admitted for preterm labor ng nakaraang Thursday. Before discharge pinag BPS UTZ ako, malikot at malakas nmn dw po heartbeat ni baby. Naka8/8 din sya sa fetal score nya. My concern is, ang Estimated Fetal Weight ni baby is only around 1.6kgs, reading through TAP and sa mga friends din na nagkababy na parang naliliitan pa sila kay baby. When I found out I was pregnant I weighed around 52-53kgs lang, regular checkups ko is ok naman pati results. Naglalaro lang ung bigat ko sa whole pregnancy ko from 53-59kgs. Last check up ko before maadmit I was 58.5kgs. Ok lang po kaya un or I should be worried? I'm petite, 4'11 lang height ko and my weight now is ung mga pinakamabigat ko nadin talagang timbang. Di din ako lumobo ng sobra bumilog lng din muka at tyan ko. Another concern nga mamsh, sa lahat ng checkup ko from the beginning tama nman ung age ni baby sa development nya which is 34 weeks na dapat, pero ung sa BPS UTZ ko ng sabado, around 32 weeks pa lang daw si baby. San po ba ko dapat magbase? Thanks