Retainer still fits - will it realign my teeth?

The retainer very well might shift them back into place. It won't really hurt anything to try, unless you are struggling to put it in or it creates sharp pain while it is in. You recognize that talking to an orthodontist is best, and I certainly understand not being able to afford to see a dentist, but you should be able to call the orthodontist that did your braces and at least get some basic guidance over the phone. After all, you probably paid thousands of dollars for your braces and saw him/her at most once a month for a few years.