when you do heavy lifts like shrugs, barbell rows, and deadlifts...do you use straps, or just raw grip strength?
If you use straps...stop. They are allowing you to keep a weak grip. Weak grip is attributed to weak forearms.
for deads, use an alternating grip (left supinated, right pronated) and then alternate them each set...until your grip strength gets up to speed.
If you're not doing those exercises I mentioned, start, as the weight will help with forearm strength & size. grip machines help, hammer curls, bloc's link has some stuff too.