Wow...you are dealing with a lot! I think you'll get wiser souls than me weighing in here (Saysusie?) but I can tell you one or two things based on my experience and the information gleaned from doctors. First, you don't need a positive ANA to have lupus. Yes, most lupus sufferers DO have a positive ANA, but it is possible to have lupus without that marker. (and, conversely, it's possible to have a positive ANA and NOT have lupus.) Secondly, there is no magic dose of prednisone that works for every person with lupus. It depends on the level of inflammation, the clinic symptoms you have, your own body's chemistry - lot's of things.
You certainly have a lot of lupus-like symptoms, no doubt about it. But, there are a lot of diseases that have similar symptoms. And, it's not at all unusual for someone with lupus to have multiple auto-immune disorders, or other diseases, at the same time. It makes diagnosis a nightmare for many of us.
I'm glad you like your doctor - keep pressing for answers and if you aren't getting them, look for someone who has more experience with autoimmune diseases.
I hope you find those answers - and the treatment that will help you find some measure of relief.
"If you trust Google more than you trust your doctor than maybe it's time to switch doctors."