I'm 5'8", Weigh 115 Pounds, Am a 32C. but They Are Saggy.

As women age they replace variable amounts of breast gland tissue with breast fat tissue. If your overall bodyfat percentage decreases or is low at the same time you can get some deflation or saggy appearance of the breasts. The solution is gain weight (a better option than having fat from one area being injected into another area), get breast implants, get a breast lift or some combination of these solutions. The photo alone of you in a shirt does not allow a full assessment but a suspect breast implants alone should suffice in the absence of previous pregnancy or overweight condition.

My response to your question/post does not represent formal medical advice or constitute a doctor patient relationship. You need to consult with i.e. personally see a board certified plastic surgeon in order to receive a formal evaluation and develop a doctor patient relationship.

With low body fat and sagging breasts, you may need a lift and/or implants or both.  It is hard to say without an exam.