I love this question.
If anything can form in your mind as a form, then it is something, is it not? Since you conceive of a form called "nothing," then nothing becomes something and since it is something it can not be nothing.
No matter how much you remove in your mind all objects so as to strip away everything in an attempt to define nothing, you will always have at least one thing, the form which is the thought of it and that form is always going to be something. Therefore, nothing cannot have a form which represents it and be nothing.
The concept of nothing is beyond the ability of humanity, of the human mind, to comprehend. Because the very definition of nothing always makes it something, which is a something which is no-thing. You see, you cannot get to that final stage in your mind. You cannot strip away the last layer of the onion to get at the core of it. It's just quite simply impossible to get there using a human mind.
This says something about the human mind, does it not? It says, that the human mind is only tactile, only functional, when the mind has a form to work with. There is not one thing you can conceive of, that cannot be defined as a form. Your mind is a machine which uses a form in order to start the process of comprehension. YOu cannot comprehend that which does not start as a form, and no-thing is formless objectively.