Great job on nailing the right pitches and intensity, two of the hardest aspects for many singers. The main issue remaining is that your tone is very nasal. Unless you like that sound I would recommend really focusing your training on opening up more space in the back of your throat.

So that would mean you might want to discontinue exercising on nasal consonants like m, n, and ng for a while since they will ingrain the bad habit of singing with an excessively low soft palate that you seem to have. Instead, work a lot on the vowels and testing for nasality through two measures

1. nose pinch test: if you pinch your nose and the sound changes, you're too nasal and you will have to increase the vertical stretch of your soft palate until the resonance is hitting below the soft palate.

2. look in a mirror: if when exercising a particular vowel the space between your tongue and soft palate closes down a lot you'll have to work on trying to stretch those two apart so that their approximation is more gradual or even both not moving toward each other at all.

This singing up and back but below a lifted soft palate thing, is a tough sensation to grasp but warming up your very high range well might help you find it. It will feel more like it's placed back in your mouth and like the roof of your mouth is lifted up to redirect the sound below your nose where it can resonate up against the soft palate and down against the tongue (not literally but that in between area in the back of the mouth is where you'll feel the sound will live). Rather than like the resonance is split between your nose and mouth and charging forward - you don't want that sensation. The correct sensation is very narrow and tall and like the back wall of your throat and upper back roof of your mouth provides a soundboard for the notes bounce off.

That is not to say you LOSE the sensation of buzziness in your face, that's a good sensation, but it should be sympathetic, not literally where the sound is being placed first.

Very hard stuff to explain in text but I did go through this process myself. I've got the nasality gone well, but it's not that simple - I'm still fine tuning my resonant placement myself, so if as you practice you feel anything different in your throat and it feels great and sounds great listening back, go for it.

Another thing that can help is to practice stretching the soft palate up nice and tall in falsetto first, where there's less tension and it's easier to manage and practice the throat shape. It will be much harder to achieve with belting but in time if you really focus on this "umbrella" feeling of a pull both upwards and downwards (mostly upwards, the downwards thing is connected with support), and placing the sound toward the back around the soft palate instead of forward in the mouth or nose, you will develop it over time.

All of this is quite comparable to the sensation of yawning but it's not quite the same so take that reference with a grain of salt. More like the upper 1/2 or 2/3rds of a yawn or something.

One last edit, I probably didn't mention this as much, but it's not just raising the soft palate up, you also need to relax your tongue downwards a bit more. The two together is the key, then you get that "can fit egg in the back of the throat" kind of space that makes for some really beautiful sounds and the great part is you can still minimize vocal tract shifting, even close the jaw more if you want, after you've established that open space in the back where the sound will seem to hang out and bounce around the most.

You can always go back and sing maskier if you want but right now I think you are overdoing it and you don't want to be limited to that sound. Your technique within it is definitely very solid, it's just I think your tone could be a lot better if you work on really getting into this open throat feeling. Other than that you're doing extremely well.

Hopefully I explained this all okay. It took me time to figure out and I'm not exactly sure how I corrected my own issues with a bit of nasality, it was never one magic bullet, but hopefully I touched on all the points that factored in.

Personally I wouldn't recommend trying to lift your soft palate and yawn... but that's just me. Instead, try dropping your jaw. Or sing a "nay nay nay" in the whiny way that you would normally do and see if you can bring that sound closer to the way you would speak it while keeping the closure. Also I think a "go go go" might help you.

A teacher will be able to solve this quite fast so I suggest you get one on one lessons.