Having problems with weight loss?

I've been working out at the gym 3 nights a week, following the Weight Watchers plan and I'm having a hard time losing weight. It's been 3 months and I've lost ONE pound. Body fat went down 2%, but for every week I lose 2 or 3 pounds, I gain it over the month and wind up with only 1 pound of weight loss. Gym workout consists of cardio or weights or both. Am I not doing enough? I tried this same routine a year ago with the same results. I was thinking of going to a nutritionist. I'm a healthy eater, but I just have the worst time losing the pounds. Three years ago, I lost 30 pounds without blinking an eye, then plateaued. Since then, I've gained it all back.