Hi Prada.
For starters, Manhattan Prep practice tests are known for generating scores a bit below those generated by either Veritas tests or by official tests. So there is a significant probability that you have made some progress via the preparation that you have done, and that had you taken an official practice test rather than a Manhattan Prep practice test you would have scored higher.
Next, as has been discussed, your having taken only two practice tests during all that time you have been preparing seems off. Beyond being a way to learn how to handle the test itself, taking practice tests tends to be a key component of people's preparation in multiple ways, ways including providing insight into what the people need to work in order to hit their score goals.
That brings up another point.
When you talk about preparing, you talk about things like "learning the material" and "understanding the concepts", and saying those things does not really describe what you need to do in order to score high on the GMAT.
The GMAT is a game, and "the material" and "the concepts" are merely components of the game. It's almost as if you wanted to learn to win at poker or chess, and so you read the rule book for a year. Hey, knowing the concepts is great, but that is just the beginning.
Going forward you need to see the test as a game that you need to get better at, and your being objective oriented is JUST RIGHT.
Probably your best next step would be to go over that Manhattan test that you took and see what you needed to do better in order to score higher. You could use Manhattan's analytics to get a sense of what topics you know best and which ones you whiffed and then get to work doing what YOU SPECIFICALLY need to do in order to hit your score goal.
In other words, you don't have to "go over the material". You are already familiar with most of the ideas that are used as components of GMAT questions. Rather you need to learn what you need to learn in order to get more right answers.
For instance, if on that test you got only half of the geometry questions right, then you could close in on your score goal by getting better at handling geometry questions. Each right answer is roughly worth 10 points. So if you get to the point where you can expect to get two more right answers to geometry questions, in a very rough sense you will have gotten 20 points closer to your goal. To achieve that increase you could go over the geometry questions that you missed, see what you needed to be better at in order to get them right, learn about whatever that is, and do geometry practice questions, 20, 30, or 50 of them, whatever it takes for you to get good enough at handling them so that you can expect to get most of them right when you next take the test.
Next, do the same thing with another thing you could be better at, say handling number properties questions, or CR questions, or whatever. Work topic by topic, becoming an expert at one topic at a time.
To score 670 on the GMAT, you don't need to know every little thing. You just need to be effective enough at enough things, and notice that I said "effective enough" rather than "knowledgeable enough". You have to be good at PLAYING this game in order to win it.
You probably should buy the rest of the Manhattan practice tests, and if you use all of them up you could move onto the Veritas tests and then any other tests as needed. Also, be sure to use the official GMAT Prep tests as well so that you get practice taking official tests and don't show up for the test and get surprised by what you see.
Here's a blog post about objective oriented GMAT preparation, one from which you might get some additional insight.
https://infinitemindprep.com/raising-you ... the-board/
Here's a source of decent practice quant questions in case you want a bunch of categorized questions. You can access the questions by going to the GMAT area and signing up for a practice account.
https://bellcurves.com
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