To add to what @pell mentioned, your light source is diffuse, which creates more subtle shadows. The small contrast between lights and darks can make it difficult to pick out the shape of those values. From the image it looks like you possibly have a light source on it, but the room being so bright is what is causing that effect. You could try darkening the room except for one light source and your reference image will be a bit easier to work with.

Nice job getting the shape of the fruit. You're obviously taking your time and observing the model. Your shadows are clean, but you could probably push those darks a little more.