How realistic is it to expect my nipples to point in the same direction? (Photos)

Thank you for your question.
The photos you provided reveal a significant amount of breast and nipple height asymmetry. This natural breast shape will simple rest on top of a breast implant and will only become more noticeable unless something is done to treat it. The breast implant simply creates a 'mound' under your natural breast tissue and cannot, by itself, change nipple and breast shape asymmetries. In your case, It would be very reasonable to proceed with a breast augmentation but you would need to strongly consider doing a breast lift on the left side as well. With this combination fo procedures, you should be able to achieve reasonable breast symmetry. Personally, I would suggest an implant placed under the muscle (dual-plane procedure) as you are quite thin and would have a more natural look with less rippling than if placed in front of the muscle.
I do hope this helps with your decision making. 

With implants to both breasts and a lift to your larger breast, I think you could achieve fairly close symmetry. Do remember that your breast are "sisters and not twins," and will never be exactly alike.

Thank you for your question.  You do have significantly asymmetric breasts.  I believe you could have better symmetry of the breasts as they sit on the chest wall as well as the nipple and areola complex with a bilateral augmentation and a modified breast lift on the left side.  I would not expect perfect symmetry but you would have much better situation than you have now.  I suggest you see a board certified plastic surgeon experienced in breast surgery.  Good luck!