Yes I agree with the post above. If you increase your dosage more side effects will accompany it. I was on 100 mg for a while and I noticed having a lot of difficulty with my speech that hadn't been there prior to starting the medication. I also noticed the memory loss and I found my classes a lot harder than normal. I feel your pain though. While being on 100 mg I noticed virtually no change in the amount of headaches I was having - frustrating for sure.
I don't know how old you are but you should be aware that at the 200 mg level, Topamax renders your birth control ineffective.
It might be worth it to keep experimenting with topamax, or it might be time to consider what other preventatives could be better for you.