Chronic high RR

Hi vets. Looking for advice. Alanza is a 4 year old, spayed kitty. Short story: she has high RR since Feb. Treated with antibiotics, steroids and asthma meds. No improvements. Did lung wash with cultures and fungal culture. All negative. Lung x-rays look a little worse each time we retake x-rays. She never responded to any meds. Now when we medicated her with Transdermal pred and inhaler, she turns purple so I've stopped meds. She eats and drinks fine, playful. WAY more affectinate than normal. Is there any new suggestions we can try? Any tests? She's just so young and I don't want this to cause her to pass. I have 5 other pets and none have respiratory issues. Most recent pic of her lungs