I'm 18 right now and I'm getting my breast augmentation at 19 for graduation, is that too young?

It is possible for someone your age to get a breast augmentation.  Please seek out a board certified plastic surgeon for an in person consultation. Regards, 

The onset and cessation of breast development will differ from one individual to another. There may also be post pubertal changes due to menstrual cycle variation, pregnancy, weight gain and loss. Some women, continue to develop into their early 20's.
The decision to undergo augmentation is a personal one as is the timing. I typically recommend that potential candidates demonstrate a stabilization of growth (at least 6 months).
Another factor to consider is FDA restrictions on device usage. Silicone implants are approved for augmentation in patients 22 years or older. If this is an issue, you may choose to delay surgery.
As always, discuss your concerns with a board certified plastic surgeon (ABPS).

Your concerns are understandable but assuming you demonstrate physical and emotional maturity, you are not necessarily too young to undergo breast augmentation surgery. In my practice, I individualize recommendations after in office evaluation of patients' history and physical, maturity levels, motivation, and evaluation of the young ladies' understanding of potential risks/complications associated with breast surgery.   In other words,  the decision whether or not to proceed with elective breast surgery will ultimately be a very personal decision that each unique patient should make after CAREFUL  consideration of the "level of concern" with her breast appearance VERSUS  the potential downsides associated with the breast surgery under consideration. Generally, best to achieve a level of physical, emotional, psychosocial, and financial “stable state” prior to considering any type of elective plastic surgery. When the time is right, careful selection of a well experienced Board-certified plastic surgeon and careful communication of your goals will be key.Best wishes.