From a BB'ing standpoint, here is a differing approach to actually eating and lifting more or doing direct arm work, and putting on actual Bweight.
Are your arms smooth right now or are they fairly or really cut?
A well defined arm can look huge, if the vascularity and striations are much more present, even though the arm may measure smaller. Think wide receivers etc.
Examples are guys like Zane, Dickerson etc. who had small arms, but they looked larger because of definition.
Another, Savickas' arms look small in comparison to some pro BB'ers but he is actually a huge man.
How big are your wrists? This is kind of a marker, on how large you can make an arm 'naturally".