Problem with small vessel

I build my first small vessel, it turn out to be quit big.

But I cant get it to fly straight.
The left wing is always going down.

I uploaded the blueprint, I hope someone can tell me what I am doing wrong.

I have 10 trusters at the back, 6 on the bottom and 6 on the top, to the left and right I have 3 each.
2 generators