It is going to be extremely difficult to raise your score by 60-80 points in 3.5 weeks, particularly given your constraints. (You said 640 to 700 but then also said, at one point, that you wanted to raise your score by "at least 80 points.")
I'm not telling you this because I think you should give up, but I don't want you to set unrealistic expectations for yourself and then stress yourself out too much. That can cause you to underperform on the test, or not do a good job on your applications. It can even cause stress that your baby will notice. (Congratulations, by the way!)
Your first goal is to take care of yourself and your baby.
Your second is to put together the best application package that you can.
Your *third* goal is the individual pieces of that application package - one of which is the GMAT. The schools aren't going to let you in if you have a 700 but the rest of your application is sub-par. They *might* let you in if your application is stellar in general but one piece (your GMAT score) is a bit below average. Think about that as you decide how much time and effort to allocate to the GMAT vs. the rest of your applications.
First, do some research (or talk to an admissions counselor) to see what your schools actually do want to see from applicants - in terms of GMAT and GPA, yes, but also in terms of work experience and so on. Try to gauge how far below the average your GMAT is for the particular scores (if it is below the average for those schools) and how high you would have to lift to hit something that is still in range for those schools, even if it's not at the top end of that range.
Next, take a practice test under 100% official conditions,
including the essay and IR sections. This will take ~3.5 hours and you will not want to be interrupted, so you may need to find someone to watch your baby during this time.
Use the below to analyze your most recent MGMAT CAT (this should take you a minimum of 1 hour):
http://www.manhattangmat.com/blog/index ... ice-tests/Also, read these two articles:
https://www.manhattangmat.com/blog/inde ... lly-tests/http://www.manhattangmat.com/blog/index ... -the-gmat/Figure out your strengths and weaknesses as well as what you think you should do based on all of that knowledge and analysis. Then come back here and tell us; we'll tell you whether we agree and advise you further. (Note: do share an analysis with us, not just the raw data. Part of getting better is developing your ability to analyze your results - figure out what they mean and what you think you should do about them!)
Because you have such a short timeframe, you're going to want to tackle your commonly-tested weaknesses. If you're struggling with equations in general, you've got to address that. If you're struggling with something infrequently tested, such as combinatorics, your strategy will be NOT to study those and to get them wrong fast on the real test. Spend your time on other questions that are more likely to pay off.
Also, because you didn't prep much the first time, you may have some signficant timing issues. (Everyone has timing issues - the question is just how significant they are!)
Read these two articles and start doing what they say:
http://www.manhattangmat.com/blog/index ... -to-do-it/http://www.manhattangmat.com/blog/index ... nt-part-1/Finally, I just wrote a new article about developing a study plan. You will not be able to do everything listed in that article - you don't have enough time - but you may want to select pieces from it to help you. The article is scheduled to be published on our blog on Monday, so check out the blog then.