Trust me, your license is valid after 6 months. The actual ruling as it states on the traffic police websites which I would look at as the official mouth piece and not some agean online newspaper gives 12 months but the actual grammar makes it out that only those need to change if they become a Turkish citizen. The word temporary visit can be translated as anything. I have known people to be here many years but they imported their furniture under the same "gecici" temporary meaning.
My wife is English and only has a UK license, she has been here for 17 years. She has a BMW and made an insurance claim last month and they never raised the subject once about a turkish license. Same to another English family 3 weeks ago.
I work closely with several insurance companies helping expats get car insurance, home insurance etc etc. This is part of my job so I do know what is going on. Never, has any insurance company ever asked for a Turkish license or never has any insurance company in all these years with all the people I know as refused to pay because of this not having a Turkish license subject.