PROBLEM GILLS SURFACE

HI EVERYONE! 

I will be really greatfull if you can help me finish this definition.

I've been working with it, but in the final part...in the best part, when I want to loft my curves, there is a problem. Still I couldn't figure out which.

I'ts enough if i send you the definition and the model?

Thanks a lot!!

Have a great day!

Lkm89.