I adopted a 5 month old lab mix. He's about 15 lbs very narrow, tan color with white on the tip of his long tail and feet. The head isn't big, his forehead has some wrinkles and the hair is very short and soft didn'tseem to shed. Do you know what he could be mixed with based just on this description please?

Also since he's part lab, should I feed him a food for large breed dog even though he's not large yet? (I feed my current puppy innova puppy food but there's one for large breeds)

Thank you!!
not a sharpei the face isn't that wrinkled, just some on the forehead..
could it be a pitt bull even though the head isn't big?