Welcome, Ellie. I can't image how hard it would be to get a diagnosis (or not!) during these COVID times.
Unfortunately, results from blood tests aren't going to be the answer - just a part of an answer.
You need to get UFCs (urine free cortisol)
Do you need to get a referral to an endo? They are the best to diagnose Cushing's - if you get one who is familar with testing. That's the important part. Not all endos "believe in Cushing's" which is incredible to me.
Unfortunately, there's no real way of speeding a Cushing's diagnosis along. And, I don't think you'd want to (although I did when I was in the diagnosis phase!) You want to be absolutely sure that this is what you have AND the source - pituitary, adrenal, ectopic, steroid-induced...
Best of luck to you and please keep us posted.