create a bombed elliptical surface

[alfredo bs 1]

Hello I am back here to ask for help
I have to create a bombed surface that in the plant is an ellipse
momentarily I solved by creating an egg and dissecting it, but the result is not perfect because I find it difficult to identify the precise cutting position to have the desired elliptical perimeter and in addition I can not calibrate the bombing that depends on the egg.
Can anyone help me?

 

[GP.]

divide into two the ellipse, then loft by selecting as cross sections the first elliptical arc, the central red arc (you only need one) and finally the second elliptical arc.

 

[alfredo bs 1]

after you told me it seems simple
Thanks again gp!

 

[GP.]

prego.