I shoot both right and left, and my draw length is close enough to the same to call it 28" either way. I would assume you are changing your alignment, or your expansion, in order to get a 3" difference in draw length. Could have something to do with your injuries. You could probably find out what it is by making a video with you drawing the bow both ways. But if you don't plan to shoot RH anymore it may not prove anything. From your description of yourself, it sounds like your draw length should be close to your LH draw length.
Of course, if you're using a much lighter weight bow LH, that would explain some of the difference.