Dr said I wouldn't be happy with result - should I get a second opinion? (Photo)

The chin implants that are currently used have very long lateral limbs that can fill out the hollow that you have. You still may be a candidate for a chin implant. You may want to see another physician for a second opinion.

Best Wishes,

Gary Horndeski, M.D.

Hello, hope you are well. Thank you for submitting your photos and questions. Chin implants come in many shapes and sizes, and now that custom-made implants can be fabricated the options are literally limitless. I do think you would benefit from an implant, but you may want to consider an implant that also reduces the appearance of the pre-jowl sulcus. Hope this helps!
Best,Dr. Tower

From the two photographs presented, you do appear to have a significant pre-Jowl sulcus on both sides of your chin. A side profile photograph is going to be required to make a determination about which type of implant you're need, and what you're trying to accomplish. If you're only looking for width to fill in the pre-jowl sulcus, then consider a pre-Jowl implant. If you're looking for filling in the sulcus in addition to augmentation of your chin forward, then consider a a standard chin implant. There are many different sizes and shapes of these implants, and they can even be custom carved when necessary for unique anatomy. Placement of a chin implant can be performed under local anesthesia as an outpatient procedure, which takes about 30 minutes.

I’m more or less agree with what your provider said.
The mentalis or chin region of your mandible has fairly good projection, but the body of your mandible is short and lacking in projection.
Augmenting your chin in an anterior or forward direction will create a witches, chin appearance, and create a deep labiomental fold.
You also have some lack of volume on the sides of your chin. This area would benefit from augmentation whether done with side, implants or fillers.
Forward projection is tricky in your case.
Consider consulting with the oral surgeons, who also do this kind of work, but often have a stronger background and making an assessment regarding the entire mandible and the relationship between the mandible and maxilla.
Best,
Mats Hagstrom, MD