Flat/inverted nipples. I'm almost 18 yrs old, what should I do? I'm worried, is there anything I can do to make them stick out?

As mentioned by other authors, inverted nipples can be corrected in the office nicely by division of the ducts. However, many patients who have breast augmentation find that the inverted nipples are secondarily corrected by the augmentation alone, as an added bonus, with no other procedure. So if the patient is planning augmentation anyway, I suggest that the augmentation is done first (which may be enough). If it doesn't come out, then the inverted nipple correction is done in the office, under local anesthesia. 

Inverted nipples can cause functional and body image problems for women. An inverted nipple can look flat or a slit like depression or hole at the normal nipple location. There are different degrees of inverted nipples possible.  Usually correction of the inverted nipples involve division  of the lactiferous (milk ducts). Risks  of the procedure include potential loss of sensation, inability to breast-feed, recurrence of the inversion and the potential need for further surgery.  When the time is right, seek consultation with board-certified plastic surgeons who can demonstrate significant experience helping patients achieve the outcomes you will be pleased with. I hope this, and the attached link, helps.