Carbonation issues?

So I'm nearing "drinking day" on my first home brew. It was a simple amber ale extract kit from Midwest. All went well as far as I can see, save for one thing. Today is day 11 in bottle conditioning. I cracked one thinking it'd be nearly finished but instead I find a beer that's still pretty flat. Very tasty, but no head on the pour and a flat taste. It did make a little "tsst" when i cracked it. I understood the bottle conditioning and carbonation phase should be 2 weeks. Surely 3 more days won't do much good. What could have gone wrong?

Sometimes bottle conditioning can happen in 2 weeks, but don't always count on it. For the kind of beer you made, the general rule of thumb is 3 weeks at 70F. And bigger beers will take longer. Just be patient.

Try again in two weeks. Then if it's still undercarbed come back to see how to fix it. Relax and wait it out

Will do. Thanks guys. Its gotten colder here in the last few weeks and I think the slight change may have made it too cold also. I'm hoping more time combined with a warmer place does the trick.

Minimum time you should give a brew (of average, or lower OG) is three weeks at 70F. At 11-12 days it's NOT going to be ready.
You also need to give the CO2 TIME to get into solution, in the fridge, once carbonation is done. Give it 5-7 days in the fridge before pouring to a glass and sampling.

IF you're really looking to get it carbonated in less than three weeks, then you'll need to move to kegging. Force carbonating with CO2 is the only other [viable] option. But, a good many of us use the two week 'set and forget' method for carbonating in keg. You simply put the keg at serving pressure, at serving temperature (using a chart to figure out the pressure at temp.) and leave it alone for 2 weeks (or more).

You can also try gently agitating the bottles to kick the yeast back into suspension which should carb it quicker but warmer temps should help also.

Another vote for the "three weeks at 70 degrees for a normal beer as a baseline". If higher gravity or cooler temps, allow longer.

Feeling a lot better about it now. Got it warmed up about 10 degrees and will give it another couple weeks and try again. Thanks all!