here pixel i made this the three steps you proboably need to follow:
1)make the semi circle and then move the row of vertex in red down into the sphere and move the row of yellow down a little to create a smoother transition. Then you'd have to blendshape between those two pieces.
(you'll also notice i've scaled the second row of vertex out which creates the more defined bottom of the flat bit
2) Then its a matter of duplicating the object on the top righ and scaling all the vertex on the bttom to the width you want.
after that you just have to key a layer change to transistion between the top right and left in the middle row