Feeding help!

Ok I have a 12 week old and I was feeding him around 6am around 9am around 12pm around 3pm around 530pm and 9pm. He takes in 7oz every feeding. While the past two nights he has not want to wake for his 9pm feeding i have tried everything to wake him and he won't. Is around 530pm to almost 530am to long between feedings? He was taking in around 37 ounces in a day now he dropped down 33. His a little over 15 pounds.