I'm sorry that you had a rough test experience. There are additional problem sets that you can buy, yes. And you'll probably need to, if you already did the 900+ questions in the OG book that you have.
But. There's a but.
You need to make sure that you're actually learning what you need to learn from these problems after you are done doing them. You don't learn much while in the act of doing a problem. Most of what you learn comes from your analysis after you've picked your answer (or just given up).
Read this:
http://tinyurl.com/2ndlevelofgmatWas that your approach to reviewing OG problems before? If not, learn how to do that on problems that you already know and remember before you test yourself on new problems. Otherwise, you won't get what you could out of the new problems either.
Next, let's talk about timing. That starts with mindset. This is what the GMAT is really testing:
http://tinyurl.com/executivereasoningAnd this is the mindset you need to be able to do that:
https://www.manhattanprep.com/gmat/blog ... -the-gmat/http://www.beatthegmat.com/mba/2016/02/ ... n-the-gmatYou'll need to get yourself to the point that this is the default mindset you employ when studying for
and taking the test. If needed, read those articles every day and set up flash cards or posters that remind you to ask yourself, "What's my ROI here? Do I even want to invest more?"
Take a look at this for more on managing your time per question (pay particular attention to section 4):
http://tinyurl.com/GMATTimeManagementThis article series talks more about the 1-min sense and shows how it plays out in practice on real problems:
http://www.beatthegmat.com/mba/2015/09/ ... gmat-quantFor management of each overall section, I recommend what's discussed in the Session 6 Timing Strategies Interact lesson. That's better than what I have in my time management article (so, since you have access to our Interact lessons, ignore section 5 of my time management article and use Interact Timing Strategies instead).
Okay. Official problems. The big OG has >900 problems and not all are assigned as homework, so there may be a lot more in there that you can do (if you were only sticking to the homework problems). As far as randomness is concerned, just flip pages and select problems randomly.
If you pick one that you know because you've done it before, just pick a different one on that page or the next page. (And if you pick one that you don't really remember...then it doesn't matter whether you have done it before or whether it is new. Just do it!)
If you do need more problems, you can buy an expansion Question Pack for the GMATPrep software. It will give you random question sets (you can set certain parameters, such as question type, broad difficulty buckets, and # of questions). It's around $30 for ~200 questions.
www.mba.comThere's also GMAT Focus (also at mba.com). This is quant only but is *very* good practice for people who are struggling with timing / decision-making issues. Don't use it right away - get comfortable with all of the stuff I described above first and then use GMAT Focus to test yourself.
Take a look at all of that and let me know what you think!