Sorry about the last post.
If you had a verbal agreement and the rent payment portion of the signed lease states the 6 month period, you might have an arguement. However, verbal agreements are hard to defend in court but again, if the lease indicating the 6 month payment arrangement was signed by both you and the landlord, you may have recourse.
However, last month's rent was for Dec 1 to January 1. If you didn't pay, you did not fulfill your 6 month obligation, you're one month shy. You at least need to pay Decembers payment. Your 30 day notice to vacate (Jan 1) should have been sent December 1 along with the payment to cover Dec - Jan.
Pay December's payment then send the the landlord a copy of the lease, along with the communications and a demand letter (certified/return recepit) respectfully requesting the deposit be returned to you within 30 days or you will be left with no other option except to file suit for the deposit owed.

