Weird marks on my boobs

Don’t mind the writing on my boob or my gross nails, but I’ve had these marks on only one of my boobs for probably like 5 months now, I have no idea what they are, and I know for a fact they’re not scars. They don’t itch, and they’re not really painful or sensitive either. They’re also a lot more visible in real life. I just don’t wanna go to the doctor for it unless it’s not normal. I’m also in my late teens if that helps any! More are kinda appearing too, ive tried to scrub them off but they don’t fade or leave. Any opinions? I know it’s not a rash or anything*sorry for reuploading like 3 times my photos wouldn’t post in full* ❤️