My poor kiddo got her first teeth in at 3 1/2 months (!) and it hurt so bad to nurse that she went on strike and started losing weight. I HAD to supplement, but I hated doing it. A friend of mine started pumping extra for her, so at least I had that to mix in with the formula. Poor little thing was so hungry she didn't care about flavors.
Now she's the pickiest eater EVER!