Uneven areola & piece of areola missing with scarring and hyperpigmentation 2.5 months post breast lift with implants? (Photos)

Your pigmentation issues are most likely related to scarring and incomplete removal of your areola.  The pale areas around your areola are scarring, either due to loss of some tissue of the nipple there (did you have trouble healing there?), or hypertrophic scarring (overgrowth of scar). It is possible that you may need to tattoo this area if the color does not improve within 6 months.
Along the vertical scar, the hyperpigmented areas are from the skin around your areola before surgery, which was not completely removed.  For many people, the areola has pigment which slowly fades as you get farther away from the nipple.  All of this pigmented tissue was not completely removed, and this is what you are currently seeing. With time, you may get some laxity in this area which may allow further excision of this pigmented area.  It is probably too tight to do this right now.
It is always best to seek a plastic surgeon certified by The American Board of Plastic Surgery for your best options.

The "missing piece" I think the tissue is there and it will improve in appearance over the next few months as the pigment returns. The dark areas under your new areola appears to be portions of your old areola that was too large and could not be completely removed. It happens when the aerola is too large to remove completely without too much tension on final closure. This can be fixed in future with a small scar revision. I would hold off on any bleaching agents till you discuss with your surgeon. Your overall shape and result is very nice. Good luck.

You are not missing a piece of your areola. On the rt you have lost some of the pigment making it look like something is missing. In all likelihood this pigment will return. I usually suggest some vitamin E oil for this. I think the Mederma hydroquinone would be good for the hyper pigmented areas but not this spot. It is going to take a little longer for all of this to settle out, perhaps another 6 mos.