what about food or jewelry enchantments?

Start by taking off your gear and skills and replacing them one at a time. It will make it easier to see where the benefits come from (and where they don't).

Regen, if not from set buffs, can only come from jewelry, as far as gear is concerned. Make sure you don't have an Arcane piece where you think you have Robust. This is easy to do if you have multiple set combos or multiple pieces you swap out for different enchants.

Once you've tacked the gear back on, replace your skills, one at a time, and you'll see how they affect as well.

Finally, if you're using addons (Harven's Extended, etc), it may simply be a UI error showing the wrong value. Good luck and let us know what you find.

If you are using an addon to show your stats, it might be broken and showing the wrong numbers

I'm an idiot. It was my 'casual' legendary Arch-mage jewelry. I had no idea it boosted my regen that much. Thank you all!