There is a growing body of evidence that high-frequency migraines (8-14 per month) is just as debilitating as chronic migraine. Plus, there have been recent studies documenting the success of Botox for high-frequency migraine that have yielded similar results to that of true chronic migraine.
There are risks with every treatment. Any one of them could make things worse. Did you feel this apprehensive when you started Neurontin? Something else to consider is that your dose of Neurontin is pretty low as a migraine preventive. Typically the target dose for effective prevention is 2400 mg in 3 divided doses per day. You might ask your doctor about that.
Have you actually looked at the occurrence rates for adverse reactions? Do you know if you are at risk? According to the official website, the most common side effect is neck pain, which occurred in 9% of the study subjects. All other side effects combined only affected 2% of study participants. So that's your actual risk -- 2% to 9% chance you will experience a negative side effect. Compare that with the risk of other preventives you have tried before you decide on Botox.
Here are a couple of links to studies about high-frequency migraines and the use of Botox:
http://www.neurologyreviews.com/the-publication/past-issue-sngle-view/botox-is-safe-and-effective-as-preventive-treatment-for-chronic-migraine/2adfa997460ca844f79a8c099663e447.html
http://www.montefiore.org/body.cfm?id=1738&action=detail&ref=1061
This last link is to an article I used as part of the documentation I submitted to Social Security to support my continued disability. I am now considered permanently disabled and not required to completed any scheduled reviews for them.
I hope this information helps you make a decision that's right for you.
~ Tammy