What Breed Is My Dog?

This is Miles. He is almost 7 months old. We adopted him when he was 10 weeks old. He is extremely smart and very loving. He blows my mind at how smart he is really! He has turned a little protective the past month. We have been working on when it's appropriate and when it's not and he is catching on nicely. The shelter said he is an English Shepherd/Pit mix. The vet said he looked German Shepherd mixed, but I was also told Boxer mix. So really I have no idea! Sometimes I feel like he is all of the above lol.