David,

Revolve with a trim on the bottom would also have been my first approach.

Your object is not a precise machined part, so we can try a non-precise method.

Create a solid sphere. Select Show Points. Select groups of points with your mouse and move. Use the bounding box handles to spread points symmetrically. Select all points below the "horizon" and use the horizontal alignment tool to make the flat bottom with rounded edges.

This took about one minute to make.

Ed Ferguson