I also think 2 lbs./week is a high goal for someone with only 13 pounds to lose. The general recommendation is that 1-2 pounds per week is sustainable, but the high end is, IMO, more for those who have more to lose. Trying to lose too much too fast will mean that some of the loss is muscle, which you definitely DON'T want.
Also, keep in mind that muscle is more dense than fat, so a pound of muscle takes up less space than a pound of fat. That's why it's good not to just have weight loss as a goal, but to use your measurements, or a 'goal pair of pants' as your goal.
You may not see that much of a weight loss on the scale, but still be in better shape and be leaner.