What if I Don't Like my New Breast Implants?

Don't undergo a procedure that you are  already thinking about backing out of. It sounds as if you have unaswered questions and are quite hesitant pursuing.
Although the implants can be removed, your scars can't and will be a costant reminder of your surgery. 

The implants may be removed if you'd like, but your breasts may be a little saggy if the implants were on the larger size. This is because your skin may not be able to retract. However, I recommend you're sure about having implants before proceeding with surgery.

Thanks for the question -
You're right to be cautious. Surgery - any surgery - is something that can never be completely undone. You should be sure about why you're doing it, you should be sure you've found a board certified plastic surgeon who can answer all of your questions and you have good communication with.
Smaller breast augmentation is more "reversible" than larger breast augmentation. The skin envelope stretches more to accommodate larger implants and a larger pocket must be created to hold larger implants.
Scars in any size breast augmentation are permanent, whether the implants are removed in the future or not.
Be sure you've had all of your questions answered by the surgeon that you're planning on doing the surgery and make sure you understand all the risks and benefits to breast augmentation. You should never be pressured by a surgeon to proceed with surgery.
Best of luck.
Steven Williams, MD