Bottled beer not carb-ing

10 days ago, we bottled a crap-ton of beer, about 10 gallons of an oktoberfest and 8 gallons of a pumpkin ale. The Oktoberfest carbed well and is now sitting in cold storage (I know it is a bit late, but most of it will be given away all at once).

The pumpkin ale shows little-to-no carbonation. It was done just like all the other beers I've brewed: putting the hot sugar-water into the bottom of the bottling bucket and siphoning the beer on top of it. I intentionally sucked just a little bit of the yeast off the bottom of the fermenters as the beer was siphoning into the bucket hoping to speed up the process a bit.

Last night, I shook all the bottles vigerously to try to kick up some of the yeast that may have settled, and put the beer in a closet with a temp controlled space heater hoping the warmer temps would help.

But failing that, any ideas for carbing this up? I could probably borrow a corny keg and co2 and force-carb, but now I'm a little concerned about the yeast eventually fermenting that sugar and causing bombs, as well as oxygen. Will the co2 that would be forced into the beer help remove any oxygen that might enter it from pouring it out of bottles into a keg or whatever?

I was excited for it because it was pretty tasty flat (though it didn't feel "right") and because the new GF doesn't think she really likes beer but wants to try it.

In my experience I've had to wait a minimum of 3 weeks. Anything before that will be pretty flat. The amount of priming sugar used, temperature, and gravity will also affect how long it takes to bottle condition.