I see that you've had some mild successes with getting the problem fixed with your insurance. I'd also like to mention something that other people seem to have forgotten.
There are lots of clinics out there who will do simple procedures for cheaper or even free depending on the situation. You may have been able to go to a Planned Parenthood to get it removed, as I'm sure they do insertions there as well. There are also many places that offer free reproductive/sexual health care to people under a certain age (25 or 30 usually, depending on the program). They're often referred to as "teen clinics," but don't be fooled by the name. Most clinics like this have nurse practitioners who do most of the work, but they are just as knowledgeable as doctors and a great deal cheaper.
Just thought I'd let you know what other resources are there for you besides the typical doctor's visit. Good luck!