I'd keep looking. 7 inches is enough to get lungs. The buck I killed last year was the same situation. I hit him right behind the shoulder slightly quartering away, when he took off running he sheared the arrow. It took me 2.5 hrs to blood trail him 100 yards. It was a double lung hit but he didn't have an exit wound and the entrance was high. So he won't have good blood until his lungs fill up and he'll start breathing it out. I was hands and knees for 80 of the 100 finding tiny specks, then I started finding piles of foamy blood, from then he didn't go another 20 yards. He was dead within 30 seconds of the shot but I took it extremely slow because I didn't want to push him. if you have to, start making circles and try to cut his trail further out. Good luck.