I have 2 diagnosed ND children. One overweight, one underweight both food issues.
With regards to "pickiness" with my underweight child they have a plate with partitions so food is seperate. I will make sure that his plate has safe foods on, and if I think he might like try something me and his sibling have, ill put a portion of it in one of the sections on the plate. This means he wont reject the whole thing, but will leave that section. I dont put pressure on him to try it but its there.
Me and eldest had sausage pasta, he likes pasta, and sausages but not everything mixed together. So on his separated plate he had pasta, cheese, sausage with the skin cut off, and a very small portion of the tomato sauce.
He also doesnt like the "demand" of eating a sit down meal. My eldest cant stand the sound of chewing and others eating, it gives her the rage. So my daughter eats her meal in her room. My son has his separated plate on the sofa and will graze. He prefers most food room temperature and doesnt really do hot meals.
A lot of children who have extreme pickiness and only eat the same kind of food do this because its predictable. Pasta is pasta, it doesnt change. Where as strawberries for example it could be soft, it could be a bit harder, it might taste sharp, sweet, watery.
With my eldest, who is overweight, I made swaps, she too loves instant noodles, look around for the smaller packets, and try to find the "healthiest" i mean they aren't going to be healthy but you can find one that is slightly better. I swapped ice cream to sorbet. Crisps for lentil chips.
Im aware that my eldest still doesnt have a great diet, but with all her issues, realistically that just something that isnt going to be possible right now. So I aim for better rather than perfect.
The fruit and veg she does eat, can you get the same brand each time? So its more predictable. And add something she does like to it. Veg with tomato ketchup for example. Fruit with a bit of 0% fat squirty cream and a few mini marshmallows.
Id do as PP poster said and look at ARFID, maybe Autism and PDA too. This isnt to diagnose or anything but some of the suggestions work for any kid and any family.
With regards to her becoming more sensory when you raise the subject. It might actually be that theres issues she cant articulate, or is aware of, but now youve mentioned sensory issues she's realised that some of the things that were bothering her are related to this and she's now trying to navigate what sensory issues are to her and how to manage them. Which takes trial and error for anyone at any age.
I think youre doing a great job, you obviously care a lot about this issue.
You dont need to be a perfect parent, you just do your best.