I don't how else to explain this, but I have this line, kinda looks like a vein, and when I touch it it's like a tiny little dent down, but you can't see the dent when looking at the breast in any direction; only when you touch it. I'm really pale and can see my veins, but this one just looks slightly darker (really slightly). Idk if it's a stretch mark, or hormones or what, but it's stressing me out because I always worry it's the worst case scenario. It's located near my nipple and going towards to the other. It's not long. 

It also don't hurt, or feel warm, or have any redness. I have no other symptoms, and it's not puckering I don't think. The skin texture is the same as well. I just need someone to calm my nerves is I really am overthinking this

Edit: i am taking the combined pill, I never miss a day or time, and am on my last period day. Idk if this has something to do with it. I think in might be wrong, it's more like on top of it I think? I guess the closes description i could give, is that it's like a scar