Hi sstefan,
Your last post provides some information that certainly could explain the drop in performance.
1) The long commute (1.5 hours by train) could certainly 'wear you down' a bit. By comparison, when you took your CATs, you probably just sat right down at the computer and got started (without having to travel for 1.5 hours first).
2) The 1:30pm start time is relatively later on in the day. Most people do their best thinking in the first 4-5 hours of the day. Thus, if you got up in the morning, then you spent your 'best thinking time' before your GMAT even started.
3) The two 8-minute breaks are remarkably important and can be used in a strategic way to put yourself in the best possible physical and mental state to deal with the next section of the Test; it doesn't sound like you used your breaks in a particularly specific or effective way.
4) Rushing a bit through the Verbal section (because you "just want the Test to be over") is a common instinct for many Test Takers. Unfortunately, it almost always means that you're not doing enough work to properly answer the 41 Verbal questions in that section. Finishing early is almost never a good thing. In real basic terms, the Verbal section is HALF of your score, so if you don't use that 75 minutes effectively and you don't do the necessary work, then your score will drop.
Thankfully, all of this can be improved upon. You probably can't do anything about the commute to the Test Center, but you CAN train with that detail in mind. Given that your goal score is about 100 points above your Official Score, you'll likely need 2 more months of consistent, guided study to hit that goal.
GMAT assassins aren't born, they're made,
Rich