Ok, here are some updates. As you can see the lower neck is thicker and longer now. I thickened up the nacelle, mainly cause with the thicker neck, the nacelle was too thin for it to rest on.
I also made the upper neck connecting to the engineering hull. However, after looking at a picture of the actual Kelvin, I might try and design some sort of connecting junction, so it doesn't look so plain. Also, I might modify the forward upper torpedo launcher to integrate into the new neck.
So this ship isn't completed yet, but somewhat close.