Hi tush1992,
With a planned Test Date at the end of June, you have 3 months of potential study time available - which is good. Based on what you've described though, there have been some 'issues' with how you've been studying. The 750+ score is the 98th percentile - meaning that 98% of Test Takers never score that high (regardless of how long they study or the number of times that they take the GMAT) - and you have not been properly training to EARN that type of Score. Thankfully, NO Business School requires a GMAT Score that high - so it's important to realize that the score that you "want" and the score that you "need" are not the same thing.
To start, you're studying roughly 8 hours a week - and that's not very much study. While no one here knows exactly what you are capable of (as far as your GMAT Score is concerned), to hit your Goal Score, I would suspect that you would need to commit to a consistent study routine of 15-20 hours a week. In addition, working through random practice questions (or sets of questions) does not provide much 'structure' to your studies - and it's not clear whether you're actually focused on learning Tactics, patterns and the little 'secrets' to the GMAT or not.
Thankfully, the GMAT is a consistent, predictable Exam, so you CAN train to score at a higher level.
1) Going forward, how many hours do you think you can consistently study each week?
GMAT assassins aren't born, they're made,
Rich