Tricyclen

I am a 16 year old girl & I started birth control about 10 months ago. I started on Tricyclen lo & then my pharmacy just switched it to the no name tricycra lo. I missed my period that month & have gained 30 pounds. I'm not sure it its from birth control all together but I didn't NOTICE any change in my weight until after the switch to the no name brand. Anybody have a similar experience ? Oh & I've been trying to work off the extra weight but nothing seems to work. Help!!