Staying at Ayfer abla's place was the best decision!
If you want to have a great experience with a Turkish family and know more about the local context, highly recommend you to stay here. The apartment is very cozy and clean. Ayfer abla is a very kind and hospitable woman, who is always interested in how do you feel at home. She can recommend to you some good places and how to get there. As a young woman, it was very safe and comfortable to live with her.
The location of the place is perfect. Bars, cafes, restaurants, and everything else you can find here. Also, there is a well-known breakfast street, where you can try all types of Turkish breakfasts. The Bosphorus is 10 min walk and all the public transportation is nearby: ferry station, bus station, taxi, and metro. Besiktas district is usually crowded even at night, so if you are a woman, it is safe to walk alone.
I would stay in Ayfer abla's place every time I come and will recommend it to everyone :)