I managed to delete this post the first time I drafted it, so here is the short , retyped version, apologies in advance for the bluntness.
With almost 99% certainty I'd say that the answer to your problem is to learn to Frenzel. Based on what you describe I doubt that you will ever be able to improve your equalisation while persisting with the Valsalva, and why would you anyhow? because as you go deeper, regardless of your tube patency, the Valsalva will fail.
In addition, there are real risks of permanently damaging your hearing by round window failure through Valsalva induced overpressure. Valsalva is BAD.
I would suggest that you should redouble your efforts to learn the Frenzel, if you cannot find an instructor, here's what i'd suggest:
1. Read the various how to guides - go to auckland freediving club website and look at the links under equalisation.
www.aucklandfreediving.co.nz
2. The most tricky part of learning to Frenzel is decoupling epiglottis and soft palate. My method of doing this is to get a camelback, inflate it, put a big phone book on it (for pressure) then put tube in mouth. Learn to allow air out through nose and into lungs alternately. Focus on stopping air going into lungs while it flows out the nose. This is the position you need for Frenzel.
3. In front of a mirror, slightly open your mouth, block your nose in such a way that you can see the sides of it, press your tonge gently against the top/front of your mouth and make a 'k' sound, watch for flaring of the thin flesh on the side of your nose. Once you see that you are frezeling. A short while later once you consolidate that sucessful action you will strat to 'pop' your ears.
Keep trying until it happens, once you get it your diving will be transformed.
Phil C
www.aucklandfreediving.co.nz