I agree with Lovenbeer’s short and sweet summary. My not-so-short take is that it’s not unheard of for a beer to finish active fermentation in such a short time. However:
A fast fermentation usually indicates your fermentation temperature was higher than desired. Most brewers feel they get better beer if they ferment within the temperature range specified by the manufacturer. Some of us prefer to ferment at or near the bottom of the specified range. In my experience a hot fermentation produces harsh flavors and unpleasant tasting alcohols (not just ethanol, as desired). Controlling fermentation temperature will greatly improve your beer. A used refrigerator is not expensive (Craigs List is your friend) and you can build a thermostat controller using an STC-1000. Google STC-1000 for simple, detailed instructions. A swamp cooler is even cheaper.
Once active fermentation finishes and the production of CO2 slows to the point it can’t be detected, the yeast continue to do work. They eat up some of the undesirable compounds produced early in the fermentation and generally make the beer better. Lovenbeer’s 2 - 3 week suggestion allows the yeast time to finish their work.
Before I transfer my beer (to a keg) I check the specific gravity with a hydrometer at least twice, two to three days apart. When the reading stays constant for two readings (and somewhere in the neighborhood of the expected final specific gravity) I declare active fermentation complete. I then wait at least another week for the yeast to finish their cleanup work.
So, a long answer to a simple question. Your beer may have some imperfections, but it will be beer, and it will probably be a lot better than Bud. If you haven’t already found it, go to http://howtobrew.com/
It’s a FREE (older) version of an excellent guide to home brewing. Because it’s several years old it is not perfectly up to date, but it will not tell you any lies and will help you make some great beer with a lot less worry than just reading the instructions that come with beer kits. This forum also provides lots of good information and entertainment. It will also show you that there are others who can benefit from your experiences.