Hi Apoorva.
From what you said, it appears that you have learned GMAT verbal concepts but have not learned to play the GMAT verbal game.
GMAT verbal is a bit different from GMAT quant, in that, in many cases, you can increase your quant score just by learning some new concepts to apply, whereas verbal is more of a game that you have to learn to play. In other words, your verbal score may not go up just because you have learned some new concepts, such as what a participial phrase does or how a Weaken question works. To achieve a verbal score increase, you have to spend a lot of time practicing applying the concepts and playing the game.
To learn to play the verbal game, you have to develop your ability to see what's going on in the questions by analyzing many practice questions choice by choice and coming up with clear, logical reasons for eliminating or choosing the choices. Often people spend 20 minutes or more per question analyzing the choices and coming up with ways to articulate what's going on with the choices.
So, to improve your verbal performance, you need to practice a lot more, doing the questions untimed, and you have to incorporate careful analysis of answer choices into your routine.