I have to say this. My suggestion might be weird.
The GMAT seems to be improving significantly in terms of difficulty level for the test taker.
While the prep test you took online from some prep guys have been the questions in their server for almost a decade... the questions in the GMAT real exam you will take are not just new questions but ALSO with content, twists, and registar that are NOT totally the same with those in the prepCAT you took.
This is why I think the real preparation for GMAT is understanding the mind of the test creators. What do they expect of you in a question? E.g. What really do they mean by "weaken", "Most closely parallels", etc...
It's not about taking several CATs as it is about understanding the core principle of raw Arithmetic and mastering the language & reasoning in verbal.
I wish I knew this earlier. E.g a good book on fundamental arithmetic will help you increase your score than CATs.
Let me suggest weirdly that you also sample some hard verbal questions from OG and try to create questions yourself copying the reasoning in the real question. U might want to give your questions to an expert to look at. If the expert says : "This question is not very GMATlike" OR hold any reservations about the question(s), then chances are high you are yet to be at 90percentile score.
Even if you register for a new lesson, it will only rehash what you know.
Try and use any means to grab the mind of the test giver.
Use weird means if you can. go off book if you can.
Analyse a question for two days or two weeks, creating many more possible stimuli/questions from idea behind that question and exposing the question to an expert or a your paid tutor.
PS: If you didn't feel tired towards the end of the test, chances are high you got some questions wrong because you didn't think through them enough. Your mental energy level is NOT going to be at initial level if are thinking for about 4 hours.
Posted from my mobile device