Amy, first of all, congrats on kicking the nicotine to the curb!
Now, think about the options that you have right now:

1) Don't change anything; keep low carbing and wait for your body to get over the shock of nicotine withdrawal. Maybe add some form of regular exercise to overcome any decrease in metabolism from the lack of nicotine.

2) Go back to your old eating habits and worry about weight loss later (this option will likely result in the return of all weight lost and a few more for good measure)

3) Switch to a different diet plan (however, if your body is just having the metabolic equivalent of a tantrum at having its nicotine cut off, weight loss will be no easier with any plan you choose).

4) Move to a higher level of carbs and just attempt to maintain for a month or so and then have another go at weight loss.

I realize it's frustrating to not have your body behave as you'd like it to, but even if you don't lose for a while, you're doing a very healthy thing for it by quitting the nic.
My advice would be to go with option #1; hang in there and keep trucking.