I am not a psychologist…but a student in IIT Delhi.I had faced almost exactly similar situation.I had 95% in 10th.I had 58% in 12th in first attempt,JEE not cleared,failed in AIEEE.
I dropped a year…repeated boards and competitive preparation.Then i got 80%in 12th,AIR 849 in IIT JEE 2012.
I am always willing for any possible suggestions I may give
please feel free to mail me if you wish to contact me
I’ll be grateful.