What Could Small Marks On Inner Thighs Around The Public Area Indicate?

About two years ago, I noticed a few fairly small marks on my inner, upper thighs. It is right around my pubic area. (I am a boy.) They are on both of my thighs. Over the past two years, the have gotten bigger to the point where they look like one, big mark. However, they really aren t that big, really only, I d say, an inch and a half big. They aren t raised from the skin, they look like birthmarks. I am white, and the marks are a fairly light brown. They never itch. I was wondering if anybody knows what they could be. They are definitely not ring worms. I also have never had sexual interaction as I am only 15, if that helps. I m starting to get nervous about them, I hope they are just birthmarks. Please let me know. A picture is attached, too. The picture is slightly photoshopped, I blurred out some spots that were not necessary, such as hair. Thank you.