Breast size can wax and wan for the few weeks after surgery as tissues swell, edema resolves, tissues stretch and tighten. Cerainly after the first 3 months or so, your size should be relatively stable. Significant shrinking may signal a leak which can happen at any time.
Pain is variable and can occur months latter on an intermittent basis. Often this is a sharp, stinging or electrical shock type painrelated to sensory nerve stretch or injury. Usually this abvates and is not a debilitating problem. Pain related to hardening can be significant but in the face of what you describe, is not a possibility. Infections can also cause pain but your breasts would be expected to swell not shrink with infection either in the capsule or in the breast itself.
Ripple is always present with breast implants. The real question is, do you see or feel the ripples? Most of the time you feel them but may not see them. Sometimes you will see them in certain positions, usually leaning forward. The softer the saline implant, the more rippling, especially with textured implants. Also, if the implants are wide enough to project outside the perimeter of your natural breast tissue, you will see more rippling. Increased rippling and increased shrinkage, may indicate leakage.
I would review these concerns with your surgeon and, if not satisfied, seek a second opinion from an experienced and reputable plastic surgeon. You can ask you surgeon for a second opinion referral. Most reputable surgeons will be happy to do that if you are unhappy since their goals is to make you happy with your result and to determine the truth behind your complaints. A good second opinion should either confirm the original assessment by your surgeon, or suggest other diagnoses or solutions to him or her. Be wary of the second opinion who wants to take over your case to the detriment of the original reputable surgeon