HELP! How do I increase my score from 420?

I really hope it's something...because I've worked on my math skills extensively. So to answer your questions:
1) I only took the ENTIRE mock exams twice (not less for sure). I've practiced the AWA section and IR section separately. Since writing wasn't an issue for me (I recently graduated from Political Science at Western so essay writing was a 24/7 thing), I didn't do too much AWA.
2) Yes, I took all at home. I have a space that is like a cubicle (in my room) so I'm surrounded by the walls and face a wall while writing.
3) With regards to time, probably not. Once I took one at 10 PM at got 440, after repeatedly getting 510, so I figured it must have been the time because I was exhausted and it was after a long day of practice/studying. I took the rest at different times (usually within 12pm-8pm)
4) Initially, I took longer breaks and kept pausing the exams (like for 3 or 4 exams for sure). But the last 2 exams, my breaks were timed AND I didn't pause the exams. It was as real as it could get.
5) I did, and the one I got 570 on I had already known some of the questions, but I always force myself to 'reason' through it before selecting the answer so that I know I'm able to logically make sense of it and understand it. (ps. what does CAT stand for?)

I've already been accepted into 2 business schools, both my top choices. But the problem is my offer is conditional upon a GMAT score (it's for an MSc in Management/MIB program), and time is ticking... so I'm slightly worried after this exam. Thanks for your help! I hope we can figure this out!