Ahhh this is so common lah, especially during first trimester, a few of us mommies went through this too, memang payah! Try using a softer toothbrush or even a kids' one, brush gently je, and kalau boleh move to the back of your mouth dulu sebelum dekat depan sebab sini trigger gag reflex more. One of my mum friends swear by rinsing mouth with cold water before brushing, or try brushing after you've eaten something (not too acidic lah), sebab stomach kosong memang lagi senang trigger vomit, lepas 12-13 weeks usually kita orang dah okay sikit! Jangan stress, this phase will pass soon okay mama!