Nipples, like breasts
come in many different sizes, shapes, and forms! Whether nipples protrude or are inverted, both are variants of normal. The difficulty with inverted nipples comes when it's time to breast feed as it may make it more difficult for babies to latch. While I do not have your other nipple for comparison, your photo and description with the "pinch test" lead me to think that you do not have an inverted nipple. I often tell patients that their breasts are SISTERS, not twins. However, if the asymmetry bothers you, there are ways to evert (turn out) your left nipple more, or reduce your right nipple to match. Please do consider whether you plan on breast feeding in the future though as any intervention on the nipples will alter your ability to do so. I hope this helps.