There is some confusion about what you actually did, according to the title you shorted the bitcoin at $17k, however, in the post you state you sold it at $18k.

It would not be a good idea to short bitcoin at such a level when bitcoin has fallen so much. Of course, you can scalp but there must be a supply zone where you are trying to short. However, you did completely opposed short-ed from a demand zone ($17600)