Gaining weight on atkins... please help?

I was on the atkins diet, and it seems I keep gaining weight... I lost 15 pounds in one month... and then over the course of 4 days... I gained back 3 pounds. Why is this? I had 2 pieces of popcorn the day I gained back one pound. I also had tostitos spinach dip... (I think I had 35 grams of carbs that day during the induction phase) and then I went to a korean bbq and they put all this seasoning in the meat.... (so once again I had 35 grams of carbs) but that other day... All I had was a large coffee and a 150 slices of pepperoni (processed meat) and I stilled gained a pound!!! Yesterday, I had 4 cups of lettuce (ur only supposed to eat 2) and I had 4 cups of radish (your only supposed to eat one) but I've gained back 3 of the pounds I lost. Yesterday, I had about 5 ounces of mayonnaise... (Your supposed to eat lots of fat on this diet)