My 3yo DD has a small, but dark spot on her eyelid and a large but light mark on her hip. Neither has faded much so far and we've decided to leave them alone.
They either will fade or they won't. Worrying won't change anything. Learn about your options so you can make an informed decision about any treatments or procedures if they don't fade and try not to worry too much (I know that is sooo much easier said than done)
I just reread my post and realized it could sound flip or dismissive of your feelings. That's not my intention at all. It's just, for myself, I've found that focusing on things I can change keeps me sane. Worrying over and dwelling on things I have no control over makes me feel overwhelmed and helpless.