IdiotSlayer - seriously, relax.
We get dozens of these posts every week from people who sample beers from their fermenters, from their bottling buckets, and it's always the same thing:
You know what? 99% of the time, allowing the beer to carb up fixes the problem. Flat, warm, green beer does NOT taste like aged, carbonated beer. I always cringe when I see people giving the "helpful" advice to sample beer over and over until it's ready... many times, unfinsihed beer is flawed or even plain old gross.
Give it at least three weeks in the bottle at 70 degrees, then chill a couple in the fridge for two days. If it still has a bitter aftertaste... give it a couple more weeks. I will be stunned if the issues don't drastically improve.
Example #1: My Yorkshire brown ale was good after three weeks in bottles, though it had a tad bit of an off flavor. A couple weeks improved it. Once it hit four months in bottles, it became borderline amazing.
Example #2: My Belgian blonde ale had a bitter, boozy finish after four weeks in bottles (this was an 8.4% ABV brew). Two weeks later, the booziness was gone, and the bitter was greatly reduced. I plan to try it in two more weeks, and expect it will be excellent.
Relax. Quit trying to figure out what you did wrong. Odds are superb that the ONLY serious error you made was in drinking green beer and expecting it to taste great.