Ohhh mama, I totally get it, bloating at 13 weeks is SO common, a few of us went through the same thing and it made us look so much bigger than we actually were! The burping and nausea are pregnancy hormones doing their thing, sebab progesterone slows down your digestion. Try eating smaller meals more frequently instead of big ones, drink lots of water (sounds counterintuitive but it helps!), and ginger tea or ginger biscuits really helped one of my mum friends with the nausea part, tapi best you check with your doctor or midwife to make sure everything's progressing okay, especially if the loya gets worse.