Also, just get used to not fighting many monsters at once by yourself. There is no point to it in this game, and it's really hard too and that never changes, no matter which level you are at and how good your equipment gets.
Additionally, your class is a single target melee class, which means even when you get AoE skills later, they'll be considerably weaker than those of some other classes and not useful at all for killing many monsters by yourself.
Wait until you enter dungeons with other players - you'll see big pulls with many monsters at once and classes that are very skilled on burning them down fast
But when you are by yourself in the overworld, just stick to one monster at a time.