The amount of yeast wouldn't be the problem. Your beer simply dried out...meaning you had a good deal of fermentable sugars in your wort and most of it was fermented not leaving behind enough residual sweetness. It sounds like this was an AG batch, so I'd recommend shooting for a higher temp on this one. Not sure what you mashed at, but I'd suggest somewhere between 152-154. There isn't much you're going to be able to do with this one. You can try blending it with another beer, but I've typically not had much luck with that. I'm the sort of person to just cut my losses and dump a batch if I find it to be horrible. Why put myself through the punishment. If it's still fairly drinkable though, you can work through your inventory over time.
Not all chemicals are bad. Without chemicals such as hydrogen and oxygen, for example, there would be no way to make water, a vital ingredient in beer.