I haven't washed my bras in 6 months
Are you for real? Why have you not washed them in 6 months?
I have not worn them so I have not washed them
All your clothing should be cleaned regularly even if it is not worn. Unworn clothing can accumulate dust and dirt so it is best to wash them. This way your bras will be ready when you do decide to wear them.
Shouldn't be a problem.
It's not a major problem but you should still practice cleaning clothes, even when they haven't been worn for a while.