Enlighten me

Having my third baby and currently at 18 weeks. Pero yung tyan ko para nabusog lang sa buffet, although alam ko maliit ako magbuntis pero medyo worried ako kasi sa iba feel mo na matigas sakin malabot talaga. Ung eldest ko. 7.9 pounds and sumunod is 10.2 parehong normal delivery. may iba pabang ganito? Thanks!