I'm sorry, I don't really know whether you're normal or not. I think you should see a doctor if you are concerned, but if you are healthy, it's probably not a problem.
Anyway, I just wanted to butt in and say, despite what several people have said, DO NOT take laxatives. It's probably not even a good idea to eat mints and coffee and other things that have a laxative effect on your system. The reason for this is that if you use those things to prompt you to go to the bathroom often (and it sounds like you'd need to, with the rate you're going), your body will begin to rely on them to have bowel movements, and you'd have major problems going on your own if you ever wanted to stop laxatives/other diuretics.
Also, if you have always pooed only once every two weeks and the weight gain has only started recently, the weight gain probably has nothing to do with how often you use the bathroom.