While I'm not a doctor, nor do I play one on TV, your doctor has a lot to say about whether or not you are approved by your insurance. Your doctor will ask your insurance company if you are covered in the beginning, then you will start based on what they find out. So you have a six-month "medically-managed weight loss" requirement. This means that you must follow what your doctor sets forth for those six months, including any dietician/nutritionist appointments. From what I was told by my surgical team is the doctor will submit a report after the six months and request for an insurance review. The insurance company will review the policy requirements and compare that to the report the doctor sent. If you meet the requirements, you will be covered.
Since the six-month "medically-managed weight loss" requirement was not told to you as a specific amount of weight necessary to lose to be approved, you may be good to go with only a few pounds lost. The big thing to get from this is any psychological eating issues taken care of and learn how to portion control and eat healthily.
Your doctor will know if you have extenuating circumstances that prevent you from losing a bunch of weight, and this will be specified in his report. One thing also to remember here - if your doctor does not think you are doing what you need to be doing to be approved, he will definitely tell you. I recommend asking as many questions as you have to your team and follow what they are saying you need to do.
You can do this. It is not impossible or no one would ever go through with it. Many of us have had set-backs, stalls, gains, and frustrating conversations with doctors/insurance companies. It is all part of the process. Nothing you are doing, nor will do is a waste of time - especially if you are doing it for your health.
Good luck!