Hey, im always getting oom when i play on my shaman and it's really boring when im doing bosses

I have 1068 int, 196 spirit.

I have 2721 bonus damage spellpower
3545 healing

652mana regen while not casting
103 while casting

I have all towers up, i have water shields up

I have spell power stamina gems.

Why am im getting oom :S?