help !!! one arm smaller than other

[franklin]

help,
i been working out now for about a year and my bdy has shown great improvement
but i have a problem.i started actually working out asbout six yrs ago
and as i didnt know much about bodybuilding,i followed a friends advice who told me
that i need to traint the waker part more as i am a left hander, worked rigourously
on my right hand in fact i would work it everyday because of which my right bicep and tricewp are smaller
than my left one,in fact my left arm has more mass and right one has more
defination,i desperately need to correct this please can anyone help me out,
any help would ne appriciated,
thanx
franklin

 

[Arnold]

how drastic is the difference? 1/4", 1/2" ???