Eh, bloating at 31 weeks is super common la, your baby is taking up so much space already, plus hormones slow down your digestion, so even though you're eating and drinking, macam trapped gas je feeling bloated. A few of us had this too around that time, and smaller meals spread throughout the day helped more than three big ones, plus drinking water in between meals rather than with food. If it's really uncomfortable or you have other symptoms like pain or constipation, better check with your doctor just to be safe, but this stage memang kenapa everyone I know complained about feeling full so fast!