Aww. I'm so sorry he hasn't come back, Jess. I know you can find him, though!
Have you gone door-to-door in your nieghborhood? Several years ago, my kitten ran out the front door. He had been in the backyard before, so I thought he would most likely return that night. He hadn't, so the next day I put up fliers and ads in the newspapers. Still, nothing. So, I went door-to-door, and if the person was not home I left a flier on their door. I finally found a lady who lived about 1 block away, and she said that the girl nextdoor to her just got a new kitten! Apparently, the little girl had removed his collar & tags and told the parents he was a stray. I went over and talked to the parents, and they appologized profusely. I probably wouldn't have found my little guy had I not walked from door to door! It is definitely worth a try, to get the word out in your surrounding neighborhood and even beyond that.