There are some things to look for that might be a reason you should go to your Doctor. All women have female hormones (estrogens, for instance) and male hormones (androgens). These hormones are usually in balance, but sometimes when there is an excess of male hormones, young women notice changes like increased acne, new and heavier body hair growth on your belly or between your breasts or on your back or over your upper lip, and changes in your period. Different things can cause the balance of hormones to shift so there are more androgens floating around. One of the most common is called PCOS (polycystic ovarian syndrome). This can easily be diagnosed and should be treated since it increases a risk of diabetes and obesity.
Young women’s body hair patterns are usually set by about 2 years after you start to have your period. So, if you have had your period for a few years and now are suddenly noticing an increase in hair growth around your nipples and in other places, that would be a reason to go see your Doctor. Nipple hair alone, if it’s pretty much always been there, is probably just your normal. But as with everything, your doctor knows your health best, so this is a good thing to ask during your annual checkup, or sooner if you are worried.