Worried about skin cancer

I’m 34 female and I am trying to get an appointment to be seen by a dermatologist, I’ve been waiting for several offices in my network to call me back so I can schedule and obviously it’s gonna have to wait until next week as it is Saturday currently, but my anxiety over this is making me wanna post about it here.

The first pic is from September and the second I took today. This mark has been on my back for years, maybe five uk really not sure when I first noticed it. I keep forgetting it’s there because it’s in the middle of my back and I never look at my back. I’m really upset with myself for forgetting it was there because I’m so worried that if it is skin cancer that it’s too late. I know that you can’t diagnose based off just a picture alone, but I figured maybe it would make me feel a little bit better to post about it here. Pic will be in the comments, thank you.