Ah, now I see the struggle. I'm guessing you run out of cards quickly in your hand, right? That's because you have too many 1-2 mana cards. By turn 4, you can probably play everything in your hand, but then you're out of cards.

You definitely want more 1-2 mana cards in your deck compared to higher mana-cost cards, but you want some cards in the 3-5 slot, too. Usually two cards at the 6 mana slot. This is basically so you have something to spend your mana on.

Shoot for:

6 3-mana cards
4 4-mana cards
4 5-mana cards

Try that out and see if things don't improve.