Hey there. I am also on Microgestin Fe 1/20....on my 4th month. I didn't gain any weight on the pill. As for the spotting, it has only happened to me once. It was random, and extremely light.
I HAVE had problems on this pill, I won't lie to you...it's taken my body awhile to adjust. At first Microgestin made me extremely emotional. I also experienced a very heavy period during my first month. However, now my cycles are ridiculously light....so light that it's making me quite concerned (see my thread hehe). I'm thinking about switching to another kind.
Try not to worry too much. There are a lot of benefits to being on birth control....not only will it help prevent pregnancy, but you will be able to know exactly when your period will start and end, etc. Each woman reacts differently to types of pills than others. Give yourself about 3 months to adjust. If you end up not doing well on Microgestin, tell your doctor that you'd like to switch to something else. Good luck!