Could Weight Loss, Stress and Anxiety Have Caused my Inverted Nipple?

Neither weight loss, anxiety nor stress could cause changes in the shape or inversion of the nipple. However, as this can be a sign of breast cancer, although you are young, you should seek medical attention.

An inverted nipple can be genetic and can also be due to scarring or even cancer.  At your age, it is unlikey cancer, but it is good to be checked out. If it is a benign inverted nipple, there are procedures that can release it.

In an older patient with a new inverted nipple there is a worry of breast cancer but this is extremely unlikely in your case.  Consult with a surgeon to see what he may find.  None of the other things you mentioned would have caused this.