Hey guys, i'm an ectomorphic male and have been training for almost 3 years - as you can imagine I find it difficult putting on size. I've made decent gains on my sholders, back and chest over the years but my arms have become under-developed and now look out of proportion (big body, skinny arms)

This may sound silly but should I only focus on my biceps, triceps and forearms until my arms are back in proportion with the rest of my body?