as long as you built it on the suggested angle, your OK, the higher the motor is above the wing the more the thrust angle needed
double check your work to the plans, if its right...... then chuck it in the air
I built mine to spec, and it seems like it will never get off the ground. Don't touch the elevator until you reach speed, then it will leap in the air. Also, be careful to give down input after it is a few feet off the air because you may end up stalling. The Sea otter is a great plane for flying low to the ground and doing tight coordinated turns. I would also add stall fences to the wing.
Couple things I'm noticing.
Looks like your nacelle is up-side-down? There shouldn't be an opening visible on the top, that's where the support should go through. This would make your thrust angle opposite of what it should be.
Secondly, I think your prop is on backwards. Remember whether pushing or pulling, the propeller should be in the same orientation as the airplane is facing. The easy tip is the writing on the prop should always be facing the front of the plane.