I havent posted in a little over a month because of internet problems

....
I hope I can get some good advice on what to do about Shelby's coat!! Ive posted before about her thin coat and I was told that its normal and some yorkies have a thin coat that eventually developes.... but im going crazy now!!
It seems to be getting thinner on the lower half of her back going towards her rear. She goes to the groomer every 2 weeks (for maintenance) and the groomer has also told me that her coat is too thin. She recommended that I change her food to something "Natural".... any suggestions??
I have also been seriously thinking about giving her a "puppy cut" to see if maybe her coat will grow back stronger and thicker??!! IDK what to do

Im afraid that if I go too short she will look "bald"....
HELP US PLEASE!!