Stigma "slots" problem

Char Name: Elyseia

im lvl 55 asmo sin on Lumiel..

and i forgot to finish the quest "No Escaping Destiny"

i only remembered to do so now that im LvL 55

MY PROBLEM: i only have 1 stigma slot available and thus i could only equip 1 stigma skill

*i hoped this can still be solved, or do i have to make a new sin?*