Breast lift is not a single operation and the technique used will depend on the overall size, symmetry of the breast, and position of the nipple in relation to the fold. For modest droop a round block mastopexy or lift will suffice, and for those who have a nipple just below the fold a vertical mastopexy may be best. With these procedures the glandular breast is left alone and breast feeding may not be affected, however with increasing droop or ptosis, or asymmetry, reduction or shaping of the gland to support the lift may introduce changes that affect breast feeding.
Given the fact that you are very young also consider the trade off with any scar that may be present after lift and make sure it will fit your expectation and lifestyle.
Pregnancy was often considered to be a major cause of breast droop however recent studies show it may not be as much a factor as inherited breast shape. Pregnancy can result in a upper scoop and volume loss, though the nipple probably follows its own genetically determined course.
It is hard to know your future. You may not start a family until your 30's like many young woman today. If your consultation is complete I hope you will be prepared to make a good decision.
Best of luck.
