Hi farazazamgmat ,
First of all any of the test taking software's do not evaluate your score in a predictive analytical pattern. There are no experimental questions and plus you are not competing on an adaptive environment matching up-to GMAT extent. The closest predictive test is GMATPREP made by GMAC itself.
Second, The most important thing that I would suggest is take GMAT PREP exam once. Once you have the score it will give you an accurate picture. For example if you score say 450, it is very much possible that your original score will read 390-410. This is majorly due to the fact that even in GMAT prep there are no experimental questions.
Next, with the GMATPREP score card in hand , evaluate and understand your weaknesses. I would suggest start from basics, then move over to next level of practice if and only if you mastered the basics. Simply said, however tall your high-rise building( Thought process and knowledge in our case) it is not going to sustain without a solid foundation.
Once you have strengthened your foundation, start getting your hand on GMATCLUB resources. Solving GMATPREP SC, CR and RC questions available here. It is of utmost importance to maintain an
error log while solving the questions. It will provide you the ground to understand where is the gap in your concepts.
After you are done with solving these question -sets , enrol yourself in any of the online or in-person coaching or study group available. There is a plethora of them out there. You have to choose which matches your need and most important which caters to your requirement.
To conclude, always remember that strong wind or tide have bypassed only those who have stood past them. It needs time, patience and courage and for which you are the best evaluator!