I feel exactly the same way. in january the exams went quite ok, i managed to get the A's and at the time i came out feeling ok about the exams, but these summer exams have turned out to be quite bad and i really dont think that ive even got near at least AAB to reapply.
Dont worry though- its not over till results, take the UKCAT in the summer and if you score highly, then consider reappling again if you get AAB, thats why the ucas director at my school said and if you dont get AAA then dont apply to london uni's. Clearing.. i dont know anything about, so if anyone has any ideas..