Sounds incredibly stressful, for you both!
My youngest was a fussy eater - she would eat anything white - crackers, yoghurt, cheese, bread and not much else aside from fruit. She was also breastfed until almost 4 years old, so I was never overly worried, but it was stressful trying to get her to eat other foods and worrying she was actually getting anything of nutritional value in addition to the BM.
So I can't say I know what you are going through, but I can hear how distressing and frustrating the situation is for you.
If it were personally, and knowing I had tried so many things to get her to eat other foods/textures, I would run with the ENT approach. Let her eat what she will eat - maybe try adding a child's liquid multivitamin to her yoghurt, pureed fruit/veg pouches to ease your mind a bit - and see what comes from addressing her ENT issues.
I know that I never connected the unwillingness to eat with teething or ear aches until after the fact and someone else suggested it to me, and sure enough, once those issues resolved, the eating resumed to a much better standard as well.

Good luck! If she continues to gain weight, etc, at least you know she is doing ok while you work on finding other solutions. I really hope things resolve for you soon, or at least you see some improvement.