Nausea is common for some ladies during pregnancy, even without braces. Esp now u are only in first trim. I had to stop wearing my retainer at nights during pregnancy too because it just made me gag all the way. Unfortunately there is nothing much we or the dentists can do. Just have to find ur own ways to curb the nausea feeling for eg sucking plum/ candies/ drinking gassy drinks etc. dentist also told me it is important to at least rinse your mouth with listerine each time after we vomit (or else the acid from food residue will cause tooth decay in long run)
might just b the pregnancy... wish nausea over for u soon 🙏💕