Copper Hair at Home (advice needed!)

Hello! I have been dying my hair copper at home for the last two years. I’ve use Goldwell Top Chic half 8K (light copper blonde) and half 8KG (light copper gold) with equal parts 6% 20 vol developer.

This has been working really well for the most part! However, I prefer the color once it’s faded after a few weeks.

Also, my hair is naturally light brown/dark blonde (about a level 6).

My question is: 1) Recommendations for hair color and products that will better match the lighter copper color 2) Is the color I’m using fine, but do I need a stronger developer to make it lighter? 3) Or should I not be using developer at all since I have light hair? 4) I’ve also been debating trying to go back to my natural color. What do you think looks better?

Pics for reference