You are old enough to have a breast augmentation if that is what you desire, as long as you understand all of the pros and cons. It should not interfere with your ability to nurse if the incision is placed in the crease under the breast. Any pregnancy will have some effects on the appearance of your breasts, but many patients undergo breast augmentation and years later have their babies. Discuss this with a plastic surgeon and consider your options.
Web reference: http://www.seattleplasticsurgery.com/before-after-photos/