This is why you should buy by the case.
I would shoot BB over #6 as well.
However, you're not totally screwed. You just can't take any long or high shots (which can be common this time of the year). Make sure they're in range and make sure you're putting the right lead on them. Shooting them in the butt is not going to bring them down.
I was forced to buy 2.75" #6 steel shot this afternoon as it was all Academy by my work had for waterfowl loads. How fricked am I on this hunt?