My pencil marks came out, but I am still trying to get out the gutta. Washed it by hand a few times, then in the washing machine twice on gentle cycle, and then in the washing machine again with a few towels on the long heavy cycle.
I had trouble seeing the gutta and went inside the pencil as well, next time I'll make changes in pencil first. The pencil washed out after I used a little brush on it and like you most of the colour came off but I like that look. I can use stitch to define it again and add more colour. Perhaps I didn't iron it long enough I used Pebeo setacolor.