Tejal - While I like the poses of the people you've photographed, I'm not that wild about how the images have come out, and I find the crops need work (which I think you feel might be the case as well). In general, there should be a bit of space for the subject to look into, but not too much.
I find all of these images a bit soft and in need of sharpening.
#1 I find the image is too dark and there is space above and to the left that do not contributed to the shot. I know that some photographers like like the horizontal (landscape) format for portraits (Peter Hurley is probably one of the best known proponants), but he tends to do his studio headshots this way, but generally is on a white background.
Here is one view of this shot cropped and lightened. I've also done a vignette.
#2 I find the space to the left does not add to the image at all. If anything, it would have been nice to have more material to the violinist's right. The way that her hair blends into the background is not good, but not easily correctable in post either. This is why studio photographer's use hair lights. I find that a crop, bit of dodging and a vignette help the composition. Sharpening is also required.
#3 I like the lighting in this one least of all. It is extremely contrasty and harsh. Yes the shot is dramatic, but perhaps too much so. The shadow on her arm is quite harsh too. The camera left side of the face is too harsh and the camera right side too dark for my taste. Both can be corrected for by dodging and burning and doing. I also find the contrast is to harsh and sharpening is needed. A vignette also helps a bit.