You've clearly done your research, and I appreciate that you've thought about facial proportions rather than focusing on a single feature. While measurements such as the philtrum-to-chin ratio can be helpful as a general guide, they should never be the sole factor in deciding whether surgery is appropriate. The overall harmony of your face, both at rest and while smiling, is much more important than achieving an exact numerical ratio. Based on your photos, I do think your chin appears to have mild retrusion, meaning it sits slightly behind the ideal profile. A recessed chin can make the nose or upper lip appear more prominent than they actually are, so improving chin projection can have a significant impact on overall facial balance. For that reason, if you were considering both procedures, I would generally recommend evaluating the chin first. Whether through a genioplasty or, in selected cases, a chin implant, enhancing the lower face may improve your profile enough that you no longer feel a lip lift is necessary—or it may help determine exactly how much, if any, lip lift would be beneficial afterward. Regarding the bullhorn lip lift, your philtrum measurement of approximately 15 mm is not excessively long for a young woman. Many surgeons become more cautious about recommending a lip lift in someone your age when the philtrum is already within a relatively normal range. A lip lift is permanent, and while it can create beautiful results in carefully selected patients, overcorrection can lead to an unnatural appearance or excessive tooth show, especially in younger individuals. If your main concern is that the upper lip appears thin or lacks definition, there are less invasive ways to evaluate how additional lip show would look before committing to surgery. This can help determine whether your concern truly stems from the lip itself or from the balance of the surrounding facial structures. Another important consideration is your bite and jaw alignment. If your chin retrusion is related to the position of the lower jaw rather than just the chin bone, an evaluation by an oral and maxillofacial surgeon or orthodontist may be appropriate before pursuing cosmetic procedures. Overall, based on what you've shared, I believe the chin is likely contributing more to your facial profile than the philtrum. Addressing lower facial projection first would provide a better understanding of your facial balance and may reduce—or even eliminate—the perceived need for a lip lift. At 21, taking a conservative, stepwise approach often leads to the most natural and satisfying long-term results.