The pot its in is way too big. They like to be kept rootbound, dry out between waterings. The reason its not growing is the roots are trying to fill that big pot, I suggest putting it in a smaller pot.
Overpotting is a myth. If the potting medium is too damp it is being watered too much and/or the texture is unsuitable. Those are separate issues from pot size. Commercial production facilities here plant thousands of small starts in multi-gallon pots. Deformed roots from not keeping up with potting on is the real problem.
Commercial production facilites also have the ideal growing environment, so the plant adept more quickly. Over potting is not a myth, just because you say it is. My plants are very healthy healthy and it also depends on the variety of plant whether it like being rotbound or not. WIth my experience Dracaena "song of India" like to be kept tighter in its pot.