Your breast are not fully developed until you're been pregnant and have breast fed. Normal growth is generally finished in your late teenage years to early 20's. That being said, your breast will continue to change in size and shape as you age. When you're younger, your breast are more glandular and dense. As you age, the breast tissue gradually become more fatty. If you gain and or lose weight you'll notice the size and shape or your breast change. Gravity will always affect your breasts.
Please speak to a board certified plastic surgeon to discuss your concerns!
You should contact your plastic surgeon immediately to be evaluated. You may have a hematoma (blood collection).
What you're experiencing is mostly likely some trapped air around the implant. This condition is generally harmless and will gradually resolve over time.