Kariva and birth control

I have been on Kariva (generic for Mircette) birth control for about 6 years now, I started when I was a junior in high school because of all the symptoms associated with irregular cycles. For the first 3 years I believed it was a miracle drug because my ability to focus increased, my cramps were few and far between, and I felt less moody. BUT...increasingly now over the past couple years it seems like the pill is losing it's effects. I also started having horrible migraines at least once a month, sometimes twice...and my doctor was not sure why, so she decided to cut me off from the birth control "just in case" and within a couple weeks I became very emotional, had cramps, and had trouble focusing in my college classes. I went back to my doctor and she put me right back on the pill...but it seems like ever since that happened, I haven't fully gotten back to the state I was in before the migraines started. After seeing this thread, I am wondering if withdrawal may be the cause of how my body and mind felt after going off the birth control...maybe if I had held out longer, those symptoms would have died off. OR, maybe the birth control dosage needs to be increased, but I'm worried that could make things worse or increase dependency later on.

Does anyone have advice about what would be the best course of action? My doctor seems smart, but I feel like no one really knows the answer to fixing "myself", to feeling at least sane again...and I really need these migraines to go away because they are getting worse and becoming very hard to handle emotionally, and physically...and financially.