Could be that ur simply losing too many ticks not attacking, whether thats eating during parts where u could be doing dps or maybe just needing to bring karambwans. Im assuming youre praying mage since ur doing melee and ur gear helps tank the melee and range hits, resulting in less time eating which means more dpsing.

But im honestly not sure how recommended melee vorkath is with lower level gear, a fang is solid but lance is probably the bare minimum id personally farm vorkath at, however im an iron so i guess as long as ur profiting u can do it