K.C.
Well, this is what I've been doing and it has been successful so far. It's also how I lost the weight when I was joining the Navy. (I'm 15 weeks postpartum btw)
1- I drink alot of pop too. I can't drink water. All I taste is nasty canteens from bootcamp. lol. Anyhow, for the caffeine headaches, you must taper down slowly!!! Or take caffeine pills use tapering on those. But, since your body is used to that much, I wouldn't do it any other way. I had to do that when I was pregnant. It takes awhile, but much better than being in pain.
2. As for exercise, I do not ever do my exercise in big chunks. I do 5-10 minutes here and there. My son used to never sleep more than 10-20 minutes, so it used to be impossible. But, if you do those intervals (assuming you get your heartrate up) than it'll keep you burning the calories. Get some ankle weights. Those are great, and you build leg muscle which helps burn calories. I like doing the Wii games for exercise when I have time or pick my son up and dance.