Landlord asking for rent beyond the notice period

Dear Sir I had been staying in a rented apartment in South Kolkata since Sep 2016. The rental agreement had been renewed every 11 months, the last one being in Aug 2019. Following are the clauses in the agreement Clause # 4 : There will be NO lock in period of six months, if the LESSEE decides to vacate before six months then LESSEE shall NOT pay six months rent before vacating. Clause # 9 : Notwithstanding anything herein before contained either the LESSOR or the LESSEE shall be entitled to terminate this agreement / lease by giving to the other 2 months' written notice in that behalf. The lease / agreement shall stand automatically terminated on the date so mentioned in such notice. On such termination, the LESSEE shall quit and deliver vacant possession of the Schedule property to the LESSOR on the LESSOR simultaneously refunding the amount of security deposit without any interest. I had served a 2 months' notice in writing to the landlady on 6 Oct 2019 stating that I would be vacating the flat on 7 Dec 2019. I have already paid rent till 7 Dec 2019. However, the landlady is asking for full month's rent for the month of December 2019. My questions are 1. Isn't this a breach of the terms of the contract? 2. Doesn't this amount to unfair and illegal practice? Kindly advise.