Step 1. Go see your regional flight surgeon.
It isn’t that he/she can give you a special issuance, because they can’t, but they can look over your history and make a call to OKC to the neurology and/or neurosurgical consultants and then give you an estimate of the likelihood of you EVER being cleared for 3rd, 2nd, or 1st class of medical just based on the history to date. They can also let you know how long you are going to have to go seizure free with a normal neuro exam before they would even consider you for a SI.
Reported incidence of seizures after shunt placement in the medical literature is all over the place, from 5% to about 60%. The longer you go without one, the less likely it is to happen, but there are few predictors other than history which just plain takes time.
Almost one in four shunts need to be revised in the first four years after placement which restarts the clock altogether.
Don’t get me wrong, I love to fly too, but try to understand going into this the hill you will need to climb, the time it is going to take, and the probability of success. Get that information up front, before you commit to tens of thousands of dollars and years of effort.