Way to go, Sara! Congratulations to you! You are doing great, and have got the right attitude going for you.
I agree with John, I don't think you'll have a real problem with your weight, as you are pretty active physically to counter act the slower metabolism. I quit almost 23 months ago, and I did gain about 13 lbs, (but I also was battling thyroid problems). I have now lost 8 lbs, and I know I'll get back down to my pre smoking weight. See, I'm 50, and I had quit many, many times over the 30 + years that I smoked, and I went back to smoking too many times, as I wanted to always be slender and looking good. But when you start getting older, you realize, hey, either do it or die! I chose life/health, but wish I had just stopped for good when I was young, like you. Health is more important than one extra pant size!! You can always lose it later girlfriend! But I think as long as you increase your exercise, you will be okay. And NO, I did not just gain weight from quitting smoking alone, I DID gain weight from eating more, and more bad foods.
Best of luck, and keep it up!

hugs...
Deda