Hi Anshuman,
First off, stop trying to penetrate into the body with awareness for now. You have not reached the stage where your mind is subtle and sharp enough to feel sensations inside the body, so it would be preferable to leave that for now. Work more on the surface of the body feeling whatever sensation you can. In case of areas where you feel no sensation, wait for some time and check in a relaxed as well as alert manner for any sensation that may be present. I repeat, check in a RELAXED and ALERT manner. To relax, to soften, is very important in this practice. If still no sensations, doesn't matter, move on. Keep working patiently, persistently and diligently as the Teacher says in the course. Why do you keep saying you have spent over a year in practice and still not getting what you desire? Check within yourself, you don't need to answer to me. Is it skillful to keep tab on the length of time you have spent so far on the practice? It doesn't matter how much time you have been doing Vipassana. What matters is you are sticking to the practice day by day, making appropriate changes to the practice as required from time to time, so that you eventually master the skill of being focused and mindful to everything happening within the framework of your body. I said "eventually", since there is no precise time that can be predicted by anyone regarding when each stage of practice is reached by each person. It varies from person to person.
Earlier I said check for sensations in a RELAXED and ALERT manner. That is another way of saying to maintain equanimity. Consciously relax your mind's resistance and grasping when there is no sensation. Consciously relax when there is intense and gross sensation. Consciously relax when you find that your mind is looking for some specific sensation which you don't at the moment feel. Feeling bored is NOT equanimity. Feeling frustrated is NOT equanimity. Feeling like reaching a dead end when you think you have invested over a year for practice, is NOT equanimity.
I feel like lot of small ants are teeming on my face, my chest, on my skull and other parts of my body which feels very bad and ugly.
That is judging the experience of the moment and aversion to the sensations you feel. That is NOT equanimity.
This happen every time and after lot of effort and not getting scanning the body point correctly I get somewhat irritated...
Feeling irritated is NOT equanimity.
I hope I gave you enough pointers for now. Continue your practice.