wait, you've done MORE problems that I have and you're worried about taking the GMAT?
I would suggest you take GMATPrep1 and PowerPrep1, and see how you do with those scores. See if you're making mistakes because you don't understand concepts, or if it's because you're not used to taking CATs or doing GMAT problems anymore. If the latter two, take a bunch of the Manhattan CATs (you get 6 free with your SC book) and see if you improve. re-do some of the hard OG problems (last 1/3 of each section) and some kaplan
problems, then take GMATPrep2 and PowerPrep2 and see if you improve.
You should be able to do it in 2 weeks if you're taking time off work.