Hi amyp,
Hang in there!!!
I'm not going to pretend to have all the answers, but we all know that there are people who score in the 700s without even studying for the GMAT and there are people who score in the 500s who have studied lots for the GMAT, it just depends. It's a different experience for everyone.
Statistically, our poor scores were flukes, and the next time we take it we should hit our averages from the practice tests. Realistically, there might be factors -outside of studying- that greatly effected our strategy which contributed to these flukes. I, for one, was extraordinarily nervous, and, EXACTLY LIKE YOU, I put my life on hold for three months to study for the GMAT, not going out with friends, not having a life, skipping movies that I was dying to see, etc. When I saw you wrote this, I had to respond to let you know you're not alone.
My old mentality was: the more I study, the better a score I'll get. That is simply not true. I'm not sure what the correlation between "time spent studying" and "GMAT score" is, but I think it's really hard to take an exam if you feel like you've got so much riding on getting a good score. Someone on the board posted how they really wanted to get into HBS, for instance, that sort of mentality and stress is not healthy for me. Additionally, getting a degree from Harvard is not the key to financial success or otherwise -anyone with close friends at HBS or with close friends of HBS alums knows this for a fact. But, along the lines of having a lot riding on getting a good GMAT socre, it's not to say that that was the *only* reason we both didn't score as we hoped, because honestly, there were concepts that I needed work on, namely combinations and permutations (side note: I'd recommend Scham's "Probability" book, I got it at Borders) which would have been good time savers for me. So this time around, I'm putting less pressure on myself, spending time doing the things I enjoy, focus on things that I'm good at, hanging out with my friends more, and studying for the GMAT in moderation. One person posted on these forums who scored way below expectations wrote that they decided not to sign up in advance for the test, and just woke up and decided to take it that day (or the next) when they felt ready and got a 760. That method seems agreeable with me, if it's possible with the testing centers in my area.
Also, I've started a study group as a good means of interactive study (I found it to be very unhelpful to study alone in quiet places) and as a means of additional resources. So, maybe that'll be an option for you. I just posted a request on the "Sell/Buy/Do" forum on this site and got a reply in a couple of weeks.
As well, you asked how my sister made the huge point leap. Basically, she continued to study, but started going out more, planning short trips, spending time researching companies she wanted to work for, and going to the movies A LOT. Again, I'm not advising you to follow her path, I think the key here is:
moderation and
balance. Also, inbetween exams she waited between 6-8 weeks to retake. I hope this helps you.
Good luck!!!!!!!!!