Your upper looks great as most people are saying. I would guess that your legs are begging to grow as well. My advice would be to split your leg routine doing at least 3 - 4 exercises 3-4 sets 10-12 reps per group, quads, hams, and calves.
My routine looks like this most of the time.
Quads
Seated Leg Extensions 4 X 10-12 (used to pre-exhaust)
Standard Squats 4 X 10-12 (405lbs +)
Hack Squats 4 X 10-12 (360lbs +)
DB Walking Lunges 4 X 60 feet (If I have the gas left)
Hams
Prone Leg Curls 4 X 10-12
Seated Leg Curls 4 X 10-12
Straight Leg Deads 3 X 10-12
Smith Lunges 3 X 10-12 (If I have the gas)
Calves
Standing Calf Raises 4 X 15-20 (Full Stack)
Donkey Calf Machine 4 X 15-20 (Full Stack)
Seated Calves 4 X 10-12 (2+ plates)
Standing Free Calf Raises to burn out
Some of these exercises vary as well as do the reps. I do a 5 day on 2 day off split in which I train my hams on Friday and my quads on Saturday.
Calves I try to do at least twice a week sometimes three times if I can. I find they are a bitch to grow.
Personally I have had huge success with this type of routine and enjoyed massive growth in my legs from it. I am fortunate that the only real genetics I have are in my legs but that aside I think that this type of a routine will work for anyone needing/wanting to put some size on their legs.
A big part of training legs that I find important is to mix blood volume training with mass movement exercises. This keeps the legs loaded with massive amounts of blood for oxygen purposes and still stretches that muscle to really help it grow.
Of course eating like a staving cow helps a lot too. Good luck bro. Your looking great keep up the hard work.