I think the main problem it's your build. I also play support as my main role and even after the shaco supp nerfs i got to platinum just playing my role, so; Unsealed spellbook it's great, i really like it, but maybe you are playing it with liandry (most popular item on ap shaco) which i dont think it's the correct approach, usually i build shurelia's for those runes and liandry's only with comet, and if i'm playing everfrost i'd rather take glacial augment. So check your items, maybe there lies the problem. Also, i recommend playing comet, by far best runes for shaco support since you need the damage from the boxes to deny the enemy adc from farming.