HELP PLEASE!!!

Alexandra
So I have NEVER taken birth control pills up until now I am due to start them this Sunday... So if you are reading this please respond with whatever advice or info/personal experience you might have!!! I am worried about gaining weight on the pill... I will be going on a vacation in a few weeks and plan to continue going to the gym as well as taking Vitamin B-Complex to boost/support my matabolism as I have prior to this in order to both feel and look good for myself. So my questions are...
1. When you have taken the pill have you experienced any significant weight gain?
2. Does taking vitamin b-complex lesson the effectiveness of the pill?
Please do not pass this question up... I am asking for my fellow females help and knowledge.