Okay, just checked the website...I will be be NOT able to reschedule until May 24th, and the deadline to cancel is May 24th as well (with a refund of $105).
Huh? You should be able to reschedule at any time. Read page 7 of the MCAT Essentials 2007. I think you're thinking about the latest day you can make a change, which would be 7 days before your registered test date.