As others have said, part of the issue is that the leve you're talking about is just difficult.
Also, in looking at your character profile page, you've got Arc up to level 27, Conj up to level 4, and that's pretty much it. So your Arc is level 22, but your physical level is 22. That means that physically you're going to be weaker than mobs that are level 27.
It also means that you have almost no cross class skills to equip. Skills from other jobs help a ton in this game. Level Pug until you get Second Wind; level Marauder until you get Bloodbath; level Lancer until you get Ferocity and Invigorate; level Conjurer until you get Cure, Protect, Shell, and Shock Spikes; level Thaum until you get Sacrifice. You can get all of those skills in fewer than 10 levels. And they'll all help you immensely with your Archer.
Leveling those other jobs will also raise your physical level, so it will be closer to -- or even higher than -- your Archer level.
SE designed this game to encourage you to play more than one class. Try some of the other classes out. You might even like them.
