Hey, man, sorry to hear that. But think of it this way - my first attempt at the dreaded test brought me a 630. My verbal was pretty decent, but quant was wretched to the Nth.
A 690 isn't the end of the world, of course, but you've got a pretty hot portfolio, so improving your GMAT can only help.
You've got time, and you can do it. I think the key is to study in a different way - your current method got you this far. The next step is to identify what's not working and then zero in on that. There are some decent tracking sheets out there, and they can help you figure out if your problem is geometry or integers, or whatever. And I don't know if you're using the "tricks" that Princeton Review and Co teach, but getting religious about those can help a lot.
And, of course, spend some time in the Quant section of this forum. There are lots of people who are Quant rock stars in there and who can give you some great tips and help.
Good luck.