The left ear appears depressed because of portions of the bone (mastoid) that were removed during your first surgery. A graft could be taken from behind the same ear, and this could be modified to support the ear. There would be a small "bump" behind the ear where the repositioned cartilage would sit, but this could give you more projection.
No one ever really is able to see both ears at the same time, and even though there is a difference in the "drivers license" picture, it is rarely a view in real life that is noticeable. You are more aware of it than anyone else in the world. Nonetheless, this can be a reason to seek out reconstructive surgery and it would be reasonable to address this problem with a cartilage graft.
I would be happy to answer this question regarding a flat ear after mastoidectomy. The reason for this is that a mastoidectomy involved the drilling/ removal of a portion of the outer bone of the mastoid bone which sits behind and supports you auricle. When this is removed the ear can sink in. What can be done, we'll one option is pinning the other ear back. Another is trying to augment behind the flattened ear but thus is not an easy procedure because there is not much of a platform behind the auricle to support a graft. Consult a facial plastic surgeon with net experience to assess your circumstances