SWITCH TO ALL GRAIN. Seriously your beers turn out way better. Extract brewing is too limiting.
I think that's bad advice. I've had some terrible AG beers. I've some excellent extract beers. I would never tell someone that the fix to an issue is to brew AG.
I see a couple of issues here. I will say that my beers went from "homebrew" to good when I started controlling fermentation temperature (not room temperature, but the actual fermentation temperature) and pitching the proper amount of yeast.
The water may play a big part, so try using bottled spring water to see if that fixes the problem. Double check your recipes, to make sure the recipe is good to begin with.
so, in this order, I'd do this:
1. Post up the recipe for critique. Make sure that the hops/OG ratio is good for the style you're brewing.
2. Use bottled spring water
3. Make a starter for liquid yeast. Always. Use the pitching rate calculator. Always.
4. Don't guess at the fermentation temperature. Buy a "stick on" thermometer and monitor the temp. Keep under 70 degrees for ales.