I don't know how you drew it, so I'm not sure what I'm looking at, so I can't tell you how to fill it.
I would draw an object like that as a profile, like one half of a cutaway view.
I'd draw four straight lines and two spline curves between them. You might have to draw the curves using a different technique if you're trying to have a specifically defined profile.
Then use the pull tool and select the "revolve" option,
and sweep through 360 degrees.
Done. It took me all of 30 seconds to draw this example.
Ultra MegaMax Dominator 3D printer: [
drmrehorst.blogspot.com]