Hey,
I took 100 mg of topamax for almost a year and I never noticed any decrease in my headaches. I voiced this many times but my doctor seemed intent on keeping me on it. How long have you been taking it? Sometimes you do need to give a medication 3-4 months to see any progress. If you have been taking topamax for a longer time span and are still not getting relief I would recommend asking your doctor about other options.
I've never taken fiorinal before. I know that when I was on a really bad streak of headaches I took imitrex sometimes and relpax at other times so that I would not build up a tolerance. I would also talk to your doctor about a different kind of abortive and what you can do to avoid rebound headaches.
Just remember that everyone is different and that there are a lot of other options when it comes to preventatives. This site is a really good tool for researching medication options. Good Luck