Waiting for gastric sleeve approval and want to lose weight but already at a low BMI

Had a consultation and began the process for insurance approval for gastric sleeve. Surgeon says I may not get approved because my BMI is 36-37 and I "only" have high cholesterol and PCOS. I am afraid to lose any weight and hurt my chances of approval but also do not want to put off weight loss for 3 months only to be denied. What is the lowest BMI you would operate on ? Have been unsuccessful with any long term weight loss, tried everything. Should I just self pay and get it done or wait ?