Hi! My name is ***** ***** I'm happy to help!
You haven't reached Amazon, and I don't have access to your account, but I can help you fix the problem. Click this Link. You should be asked to login to your Amazon account. Once you login you should see 3 tabs. Content, Your Devices, and Settings. Click on Your Devices. Find and click the devices you aren't using anymore, then click Deregister. Continue to deregister all devices you aren't using. Once you've completed this, all purchases will be available for your current Kindle by default.
I hope you'll rate my service based on the quality of my answer and not based on frustrations with Amazon, with whom I have no affiliation. If you need more help please reply. Thanks!