I'm currently taking both prozac and wellbutrin xl. I've taken prozac on and off for 18 years, and it has never caused weight gain in me. Same with the wellbutrin. I just started taking them together a couple of years ago. It's been awhile since I was able to only take one med for depression. I know that when I tried effexor, after a week, it was making me feel very weird, and not in a good way.
My mom takes effexor and prozac, her doctor jokingly refers to it as "rocket fuel", supposedly it really makes a person feel activated. Finding the right meds for yourself (or your daughter) is really a trial and error process. Sometimes the first med tried works, and life goes on. Other times, you need trials on a couple before finding the right one. I hope your daughter finds one that works for her soon.