I had my hairline lowered with a advancement procedure and I got terrible scarring (photo)

The scarring you have may be the result of a surgical wound that was closed too tight which is known to form scars like you have. This area can be transplanted filling in the hairline with a forward new hairline created with fine single hair grafts in front and this will hide the scar when done properly. Similar work can be done behind it. Here are some examples of hair transplants performed for female lowering procedures which does apply to you:  https://newhair.com/female-hairline-lowering/), scalp micropigmentation can hide the scars inside your hairline easily (https://scalpmicropigmentation.com/scar-covering/#!).