Hi Sophie,
I'm so glad you found the website a helpful resource! I'm by no means in charge here, but I am grateful to contribute what I do to the self-harm blog—and I'm happy you found value in what I've shared here.
As for your cover-up options... For makeup, you'll want a foundation and/or concealer that matches the skin tone where your scars are. If you're planning on swimming or doing anything that will make you sweat, look for waterproof options or sporty brands if you can. Depending on how much you can spend on this option, you might even want to look at theatrical makeup that's made specifically to resist being sweated off or rubbed off, if that's a very big concern for you.
Also, be sure to patch test any makeup you buy—this means putting a very little on, usually on the inside of your wrist, and leaving it for a few hours to make sure your skin doesn't have a bad reaction to it.
Regarding depth—no, they don't have to be deep to last. Whether scars fade or not depends on a lot of things, but I'll use myself as an example here. My wounds were relatively small and shallow on my arms—but at the time, I thought I *wanted* scars, so I did certain things to try and make them last. I'm not sure if those actions had any effect or if my scars were going to last no matter what—but ten years later, they are quite faded but still visible if you know where to look.
I will say that if you keep tracing over the same spot, they are much more likely to become permanent. The obvious answer is that if you can stop self-harming and let your skin heal, you're more likely to get them to go away—but I know that isn't an easy decision to make, or to stick to. Still, I hope you are able to stop someday. It's worth it just to not stress over whether every new scar will fade or not—not to mention all the other good reasons to get clean, of course.
I hope that helps. I'm here if you have any more questions or concerns you'd like to share. Take care!
Sincerely,
Kim