Is this normal

Hello everyone so i took a pregnancy test ,(positive) :-) by all the apps ive downloaded they say im 4weeks and 4 days but my stomach feel like 3 months like a blowfish, im not constipated or anything but my stomach or the muscles inside bother me so much i look like im 3 months and im 125pds 5 feet is this normal i know baby is growing but is only a seed why does my stomach bother so much and i have no cramping, anyone felt like this before , im a first time mom this is all so new to me .