Did you take your prep tests in realistic GMAT-like conditions? If not that difference could explain your score being off. The AWA requires some serious thinking and concentration, then you only get a 10 minute break before starting quant, then another 10 minute break before verbal. If you're used to taking stretch/bathroom breaks whenever you want during practice tests, then it's very possible you were mentally drained and made some dumb mistakes on your GMAT verbal.
I don't know anything about the GRE, but I'm pretty sure you could improve your verbal score significantly by studying the
MGMAT SC, CR, and RC books.
What kind of studying were you doing for those 8 hours per day? Is it possible you burned yourself out?