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I will only buy books if they are worthwhile. I have the Arban, Bordogni, Tyrell, Blazevich 1+2, Conconne, Snedecor, Kopprasch, and Grigoriev. Is there anything that I'm missing?

If you can play all of those books you have in-tune, in-time, and with a good sound, perfectly every time... then yes. If not, work through all that until you can then go for more books or wait for your instructor to make recommendations. You have a wealth of material there.

You may want to get some books that deal with atonal/mixed-meter stuff and also some stuff to help the mental game (Inner Game of Tennis/Music) might help too.

Practise those that You have thoroughly. Once You play those to Your satisfaction, You should be ready to make up Your own method book.

Read artists´ and scientists´ autobiographies of influential people (artists, scientists, politians only if their career was BEHIND them when they wrote) and then some international classic literature. Melville, Steinbeck, Grass, Wilhelm Busch, Karl May there must be TONS of GREAT literature (both contemporary and seemingly outdated) to discover.
Ancient philosophers are a good source of wisdom, too.

One that seems perhaps a little too fundamental, but what I use first off EVERY DAY, is the Pares "Scales" pub by Rubank. I play through every section, though not every exercise, but it does get the mind connected with the chops without having to make a lot of mistakes. Scales are so important as building blocks to performing in the 'etude' books like Blazevich and Snedecor. Also the Cimera Etudes are challenging rhythmically and well as unusual keys and patterns. If you can handle treble clef, try the Clarke Studies.

How could I forget these?
Solo Etudes for Tuba by Dave Uber - Cimarron Music Press
Progressive Etudes Vol. 1, 2 & 3 Dave Uber - also Cimarron

These 4 are all particularly well suited for F tuba and are just fine for CC as well. (an occasional E above middle C.)

Uber embraces a variety of styles with unexpected harmonic movement.
While not to awfully difficult in the area of rapid technique, it takes good discipline to pull these off musically.
Many of the legato etudes are great for exercising breath controll, lip flexibilities and softer dynamics.

The "Solo Etudes" (12 of them)
in particular are great for working on interpretation and style. Each one is unique from the others.

I rather enjoy them.

Brass Gym