Thank you for the photos and questions. Your photo suggests that you would benefit from a lift. This impression needs to be confirmed by an examination. If your nipples lie below the level of your infra-mammary folds then you are a candidate for breast lifts. Placing breast implants and lowering the infra-mammary folds in the presence of true breast ptosis is not a procedure I would recommend. The breast implant size used by the other patient is not really relevant to your situation as breast implant size is chosen based on some specific measurements of your breasts. Please consult with an experienced board certified plastic surgeon to learn about your options.
Here is always a small difference between breasts in adult females. When you place large implants, that small difference will look smaller. At times different size implants can be placed to compensate for that
just stage the surgery. I would consider a bilateral breast aug ABOVE the muscle first. Then as a second stage do the lift if you wish to be perkier. I have done this many times and it works very well. Look for a board certified plastic surgeon
Your goal pictures are realistic. I would suggest you seek about a board certifies plastic surgeon with a lot of experience in breast surgery who can go over your options with you after an in person exam. I would think that a large implant may well allow you to get the results you want and avoid the lift.
Given your preop pictures, I don't think your goal is achievable with just implants.
I would advise looking into having a BCPS perform a lift/augmentation for the best results.
Your severe skin laxity will require a full lift and a small implant medially. Without skin removal you can not tighten the loose skin