Are you doing all that b12 sublingually orally over a long period or only a few minutes? In your lip or under your tongue? Thats alot, but if you are tolerating it, I dont see a need to lower it, some people need mega doses. I think you could trade off the 2 equally, go slowly, like 1 mg a week(though thats not really slow lol). Play with your dose to find out what is best for you, do what makes you feel best after you adjust to it and are done with start up side effects.
Make sure if you switch vitamins you are getting a roughly equal amount of methylfolate and tmg. B6 and B2 im not as worried about being as exact.
When you start adding in more supplements that are capable of increasing your anxiety, if you start to see an increase in anxiety, you could try to add in some niacinamide simultaneously if you wish to maintain the dose of whatever is increasing anxiety. Hydroxyb12 might even make you more tolerant tolerant of those things, though I wouldnt think that would make a big difference.
Yup, it will increase inflammation and that would make you feel fatigued