when I enter the time machine to recover them, it won't show me anything on the time capsule from before today.
When you upgraded the hard drive on your Mac, in effect, you then had a "new" Mac.
You can only look at the complete Time Machine backup history using the Mac that made the backups, so your "new" Mac would not be able to use Time Machine to view the backup history that was made using your "old" Mac.
Another way to state the same thing would be to say that if another user brought his Mac over to your house and connected to your network, he would not be able to "see" the backup history that was made using your Mac.
Migration Assistant can be used to move data from a single backup of an "old" Mac to a "new" Mac, but you only get one try with this. Most users choose the most recent backup made by their "old" Mac to make their "new" Mac look as close as possible to the "old" Mac.
Migration Assistant cannot move over the entire backup history of the "old" Mac. The previous backups made by your "old" Mac will not be accessible using normal means.
Since your old backups are not really useable at this point, if it were me, I would erase the backup disk and then start over again with a new backup of your "new" Mac and move forward to build a new backup history. That should free up a lot of space on your backup disk.
