Nauseous after eating?

I’m 32 weeks and whenever I eat a big meal I feel so sick! Is this normal? Im underweight so I’m trying to eat as much as possible, but I hate feeling like my belly gets so tight and hard after eating, then sometimes I have to go #2 right away because it feels like there’s no room! Almost like my baby is making my body get rid of anything that’s taking space away from her.