I redrew the feet so they have more of a leg and foot shape. The shading is not too detailed. I think the problem with your feet is exactly like you described, they are chubby and blobous. Give them some actual form, and avoid that sloping curve you have in the inside of both legs. Real legs are not like that, and it makes it so you can't distinguish between the leg and foot.
Now you asked specifically for help with the feet, but I must say there is a larger problem. You are pillow shading. Your shading is not atrocious, and you do use it to suggest shape, but the light source is directly in front of him, and things are getting darker towards the edges, with the highlight in the middle. With that kind of light source and shading, he looks quite blobby and undefined. I suggest moving the light source above him or something, and then shading accordingly. Good luck.