Why did you even consider roids when you’re the type of guy who has had no significant response to training and nutrition after three years. And considering the nature of your post, you’re likely a noob or a poor responder because it is really only advanced people that can have grown in a specific body part while a poorer responder or noob will have to become bigger overall to get bigger arms.
I know you said you’re arms, back, and legs have gotten bigger, but by you saying your arms have remained 13.5 inches while those are getting bigger at you’re stage, then something is not adding up!
I believe too many people are going by what they FEEL or what ONLY they perceive or see, which is not the same as an observer sees. There’s no other way to put it because considering one sees oneself everyday, it is very difficult to see some changes that another person will or what one can see in comparing old photos to recent ones.