How much do you weigh and how big are your arms?
Your arms should grow in proportion to the rest of your body. Do you rely heavily on straps for your back work? Are you hitting the big basics hard (Squat, dead, bench, row, chin, dips, OHP)? Are you eating enough Kcal to promote growth?
My arms are a genetic weak point for me. I have long arms and short muscle insertions. It sucks, but I deal. My forearms have really grown a lot recently just from losing the straps and using a hook grip on deads and rows. Hanging ab exercises have helped my grip tremendously too. My grip feels rock solid on all lifts and more importantly my forearms are growing. Revese BB curls, hammer curls, and pinwheel curls will hit your forearms hard too. I like 8-15 reps for these. Always squeeze the life out of the BB or DB when lifting.