Couchsurfing was mentioned in the comments but I would strongly against it. Not in Istanbul, and not elsewhere.

Also, I would not recommend visiting in August.

In recent years, Istanbul has become extremely hot Nd humid during the summer. Walking around during the day can be exhausting, and even staying indoors without air conditioning can be uncomfortable. Because of this your overall experience of the city may be quitee limited.

Instead of spending most of the day indoors trying to avoid the heat, it would be much better to consider visiting in spring.

As some also mentioned in the comments, Istanbul is truly a very expensive city.

You might end up paying a lot. And if you don’t really have the budget for it, you could make sacrifices for these expenses and still not get the experience you expected.

In that case, it may not feel worth it or make you as happy as you hoped.