Can I reduce the size of my chin with liposuction? I assume there is fatty tissue that surround the bone?

Liposuction will not remove enough fat to make a noticeable difference and could cause problems with your skin contour.
You're only real option is to have a bone reduction.
Some plastic surgeons maybe comfortable doing this procedures while others may not.
This procedure is also locational he done by oral surgeons who have training in maxiofacial surgery. 
best,
Mats Hagstrom M.D.

 Hi, I have performed many facial shaping procedures, including Facial Liposuction, Cheek Implants, Chin Liposuction and Chin Augmentation with dermal fillers or silastic chin implants, for over the 30 years.  Non smiling photos of your face from the front and side would help in the evaluation.  There is no significant fatty layer over the chin but there is fat below the chin in the neck that can be reduced using liposuction.  Liposuction should not be performed over the chin itself as it can result in muscle damage and skin contour irregularities.
Hope this helps.