When I put the transmission in reverse it gets little heavy and makes a heavy but not loud sound and when I shift the stick to drive then it runs smoothly and perfect with no sound at all. Why this happens in reverse. Is there any problem with my car??

Replace tranny fluid and filter with the recommended fluid...

Then tell us what your reverse gear is doing?

Does this help any?

it could be that you pulled your transmission,if its feeling heavy and not pulling as well then yes your transmission mite need to be replaced soon.i had the same problem.