Your back looks OK, but one like yours can be built in about a year, and also be natural. Your level of muscularity absolutely does not need drugs, we need to look at your training.
Lets turn back to your chest. Like you, chest is a weak body part for me. Chest and biceps. In the contest photo I posted my chest was fair, but getting it to that point took a lot of work. The problem I had, that I see in many, many othjers at the gym is their chest routine consists of going as heavy as possible on bench press, w/ terrible technique (bouncing, arching, etc). I am positive that 99% of your bench puts a load on your shoulders and tris, and your chest is left largly unstimulated.
Like I said, I had the same problem. Here is what I did, and what I suggest for you. Do an all dumbbell chest routine. Before doing a set, lie back on the bench, squeez your scapula together, pull your shoulders down and back, and lift your chest up high. Close your eyes, and make a mental connection w/ your chest. Take as much time as you need to make that connection, and don't worry about what other people think. Once your mind is 100% focused on your chest, sit up, grab the dumbbells....(I rarely went over 80 lbs, 100 if on gear) put them at the end of your thigh, and sit back, bringing the dumbbells up in a position to do your set.
This is the critical part: You must get everything back to the 100% mental connection w/ the weight you had moments before. Your must "feel" the muscle completely. Slowly lower the weight, control it, then explode up. However, you must keep your technique perfect. No arching. You should get at least 8 reps that are technically perfect. You are hard taxed, the muscles are burning. It is OK to then cheat in order to get the last 2 reps. Better yet, get a spotter and that way you will not need to cheat at all. In any case, you must put 100% into each working set.
Do dumbbells for both flat and incline work. Do only 3 working sets each, 2 warm ups on flat, so 5 sets total and then 3 working sets on incline. I use a machine for lower peck work.
I think you said somewhere that I only looked the way I do because I cycled year round. Over the last 8 years, I was completely clean for 5 years, on trt for 2, and in this last year I did 2 cycles. Yes, steroids will do a lot for you, but only if you are stimulating the muscles to grow. W/ out engaging the muscles more fully, your arms will get bigger, but chest stay the same.