How on earth can I carve this up 😭🐶

This is my 5th rug. I’m just having trouble with the final stage. I think I used different types of yarn & find some are harder to trim than others? Or perhaps my trimmers need a fresh blade? I’m worried to trim it down too much as well - not sure what’s right.

I also chose 4 shades of grey, 2 of which I can hardly tell the difference between because they’re so light 💀 I’m under a tight deadline & I’m afraid it’s not gonna be as detailed as I intended it to be 😮‍💨

Tips & tricks & carving advice very much welcomed 🙏🏼