Surface from 3 curves

 From:  pafurijaz
11439.5 
Or you can use for this kind of task FreeCAD, that has the ability to make surfaces from edges, in this case the curves you provided and other three to close the contour.

image Moi3Dt

image FreeCADt

To make it I've converted the curves in the Part Workbench into wire then I used those new to Make Face from edge, and it's done quickly but FreeCAD need a little effort to be used, in some cases can help.
Greetings