A manual way to tell if your Time Capsule has the older backups is to mount it manually.
In Finder, in the Shared area, you may see your Time Capsule listed there. Mine's called Router (original, huh?) If you click on that, you should see a folder with your data, and in the folder, a sparesbundle file that's your actual backup.
If you double-click on that, it should mount under Devices in the Finder window. If you click on where it's mounted, it should hopefully show you a lot of different days of backups.
You can manually retrieve data that way. If it's not showing up in the GUI, I'm thinking you switching account names may be why. Maybe create a second account on your Mac with the username that you used previously, logon to that account, and see if Time Machine sees everything for that.