I had the exact same problem as you in the first trimester. I was about to try Metamucil but because of m/s I was unable to stomach the drink. I ended up having a sprinkle of psyllum husks (same as what is in metamucil) on my high fibre cereal in the morning. I found this did the trick for me. Just be careful when you start using it to only start with a small amount and then gradually work up to a tablespoon. and like the others said make sure you drink plenty of water.