Fire skills with Mercenary don't feel rewarding

This is my setup and my damage output in the hideout:




100,000 DPS in hideout + 51,000 from the ammo (that goes to 140,000 on full attack) should be enough to feel pretty good as damage and killing bosses at a good pace.
But in reality is not what I see. In action it feels way slower than the cold damage from a ranger with more or less the same damage output, for example.

See, my point is not the numbers. Its the feeling while playing.
It feels way more weak than it should with those numbers.

And I did everything I could with gems and passive tree, considering there isn't much fire passives in the region of the mercenary.
But again, with I have and with those numbers, it should at least feel confortable, mediocre, capable. I'm not even talking about deleting bosses, just enough to be a shorter fight.

Edit.: TLDR: The numbers seems its alright but the feeling isn't. It feels i'm dealing less damage than I should with those numbers.