Hi! Not mine, but my younger brother is level 3 autistic - he is completely non-verbal and as "severe" as it can get. He had little difficulties with crawling/walking, but he had no response to his name being called or saying "no" or any sort of shouting, we thought he was deaf very early on. He rocked a lot and held his hands together while swaying whenever he was excited. He also showed little to no interest in any sort of human interaction, and only got excited when there were flashing lights, bubbles, or something visually interesting happening. He was on soft foods for a similar amount of time as your little girl but soon moved on to be fine with fries and chicken nuggets (not the healthiest but all he would eat), which became the only solid foods he would eat for years. He was diagnosed just before he turned 3, he had said a few words at that point, but he soon decided he no longer wanted to speak at all and hasn't since, he's 17 now.
HOWEVER, I genuinely think his case is extremely rare, he is in a special needs school and has been held back 3 years.
I know people who have had kids who were similar to my brother when they were toddlers and then progressed to just have some social difficulties, fully able to speak. I think it is so hard to predict what they will grow up to be like. We're in a lot of autism support groups, and they can be really useful if you're having a hard time navigating it. I wouldn't worry or panic just now, slower development doesn't mean they are bound to be non-verbal forever. Sorry our story is such a downer - but just because he's non-verbal and in a bit of his own world, he's still a joy to be around, and he did become accustomed to cuddles eventually.
Wishing you love, I hope the doctors become a bit more helpful soon! Remember as well a diagnosis isn't the end of the world, there's so much support out there now.