You should make the shape bigger than you need it and then trim it back. Don't try to make it that triangular shape. Taking a surface to a point causes the surface to pucker, and it becomes hard to control. CAD prefers four sided surfaces.
Plus, see how bumpy your surface is? Use fewer splines, and fewer points along the spline. And then use curvature combs on the spline to prevent the spline from flipping convexity in/out/in/out/etc. Use the reflections to help you see what's going on with the surface.
Thanks very much, I'll give this go. appreciate it!!