OLED DISPLAY USING SPI
Pin definitions in your code seem to be mixed up. If Adafruit example works fine with your setup, you should keep the pin definitions Adarfruit uses:

#define OLED_MOSI   9
#define OLED_CLK   10
#define OLED_DC    11
#define OLED_CS    12
#define OLED_RESET 13


Also, you are using a deprecated constructor. It is recommended to use a constructor which explicitly specifies display size.