Matching one single veneer to the remaining natural teeth is one of the hardest esthetic problems in dentistry. I believe this single veneer could be done to match a bit better. More whitening may help but still unlikely to satisfy your desires. If you love the looks of the one single veneer then having the natural teeth veneered to match, could be an option. That means 7 or so more veneers. Ideally you would align your teeth (braces/ Invisilign/ other) a bit and have a well trained esthetic dentist match the single veneer. Keep smiling.
Veneers are great for lengthening and making slightly crooked teeth better aligned. However, with the prior root canal and the discloration you may be better served with a full coverage crown. Also one of the hardest esthetic challenges in denstistry is to match one single tooth to the rest. You will want to find a dentist that is trained in esthetic/ cosmetic dentistry.
Hard to tell what can be done for your bite without a full orthondontic (braces) evaluation. Some bites can be altered prior to growth spurts, some after. Some, regardless of age, are best corrected with surgery.
I would suggest seeing a dentist in order to have professional whitening trays made. The store bought strips will often only bleach the front teeth. A professional bleaching system can bleach all of your teeth. Smile on!
I would suggest to see a dentist to get professional whitening done. There are many versions but all professional types are safe and effective.
