So i was playing a thief type and trying to just use bow and daggers. The tougher monsters were super hard since the daggers dont do much yet, so i guess early on as a thief you gotta go with some other setup besides daggers?

Daggers are still tied to One-Handed. So use a sword until you level up and get more powerful daggers.

Being a thief has nothing to do with weapon types, so swords are as viable as long as you can backstab with it!

I joined the thievesguild after riverwood village, so i started as lvl 1 as a assasin/thief set up.
I always use a bow a handfull arrows with a coiple of poison potions.
I also uses a sword as like you said, they are no powerfull daggers yet.
Invest in sneak and archery. In the thieves guild you can recieve a quick training of sneaking, lockpicking and archery.

One of my friends told me to see a mage to enchant a dagger to make it powerfull, but i didn't tried it yet.