I’m not an expert in migraines or teeth clenching issues, but from what I know, among the other problems, these two can also be contributors to variety of symptoms.
Teeth clenching, bite misalignment - they may cause distortion in the whole body’s posture and proprioception:
As for migraines, my opinion might be a bit “against” the typical doctor’s, but I believe, any migraine is a result of something else in the first place. Blood flow issues is one of them.
In general it’s a pity that the neurologist brushed it off. For one, I can understand the whole situation. This surgery is always a risk, no matter what some people here on the forum or somewhere else may say.
It may help to go to an Eagle’s syndrome (and other similar/related conditions) specialist to get it properly ruled out. While looking at your scans, they might be able to find something less common, maybe even beyond anything we heard here on this forum.
Regarding the styloid processes, IJV compression… They do look a bit affected. Styloid processes do look hypertrophied too, so it’s a good idea to keep looking into this possible condition too, unless it can be completely ruled out somehow (e.g. by using lidocaine injections into the tonsillar area by someone with experience doing these injections etc.)
But I guess, you will need a lot of patience and determination… Often these conditions are a long journey until someone finally finds the culprit(s).
Another area worth checking is TMJ disorders.