Looking at the picture I'd consider this 3 separate shapes:
1 cylinder type shape for thumb (only needed at the end)
2 lower outer shape with upward protrusion
3 inner hollow shape looks like its sanded into a bowl.
Model these 3 separate with enough extension outward.
Next in the topview draw 2 freeform curves to be projected with history enabled. These projected curves one for each large shape define the edge from where the 2 shapes will be blended with a blendsrf.
With enabled history you can keep editing both the surfaces and curves untill you feel like you have a good setup.
Than on a copied set, trim excess surfaces and create a blend surface between them.
Undo and refine untill satisfied.
As a last step boolean out the cylinder type hole and blendedge the edges.
Hope this makes sense, but unlike you I'm on my phone on a Sunday evening
You might want an extra surface to cut off the bottom flat and apply a blendedge as well
Also you might want a projected cus curve for the inside hole as well and use a blendsrf there too