M.C.
I am not sure if this will help but my daughter did the same thing.
We made her food in the beginning and processed all the veggies and fruits but once she was eating more solid foods she suddenly no longer wanted any wheat/whole grain warm cereal nor did she want any fruit cut up or veggies.
She also made the gag sound, which made me feel bad and confused that she ate all this stuff before but no longer wanted it. She went through phases of possibly turn into a piece of: pasta, grilled cheese, bagel. We started discovering sneaky ways to incorporate vegetables without her knowing into the food we cooked. To this day she gags at anything that is baby food consistency except for mash potatoes and gravy which is what she may turn into now either that or a cheese quesadilla. She is much better now and did kind of "grow" out of it. They will go through phases but keep offering it to him or including it on his plate.
One trick I did discover for the veggies was to put a little sesame oil in the pan when I make fresh spinach, green beans, or carrots with a tiny bit of light soy sauce but not to salty (just test it). We are no big on the canned stuff. If you use a can I might drain the liquid first. The only canned thing she liked was the mixed veggie one with little square potatoes in it.
She also liked some veggies with a little butter and maybe a tiny bit of salt.
Oh and she always wanted to eat what I was eating so every once and a while she would insist on eating my food while I sat with her. So I would eat my veggies and then she would want some too. Sometimes it worked and sometimes it didn't.
The feeding himself with the fork and spoon. I would talk to your pediatrician about milestone markers. But I have always gone with the theory that kids learn and grow at different levels and if the Dr isn't worried about it then I was not worried about it. He may be slow at his dexterity for now but then later is the smartest kid in the class at math time.
Don't let them put to much pressure on you. Just reassure them you are working on it at home as well.
My daughter did not use a utensil to eat until after this age as well. She would try then give up and scarf it up with her hands. But when she did do it on her own, we would clap and give her praise Yay! your a big girl! Good Job!
Hang in there