Though I'm not a single mom (or even a married mom), I can help you out a bit with the cookie thing. Clean out your house. Rid it of everything that is "bad". Of course, you can have cookies and such in the house, but not a lot. Read around, learn about the best foods to have around and, no matter what, you'll always be reaching for something decent. You should do fine if you want to. Now you've got this site, and everyone here is very nice and will help you out a lot.
Good luck! Oh, and it is possible to loose 10-12 pounds by Valentine's day. Just make sure you do it the healthy way. No starving yourself or things as such.