had blonde highlights on ma mega drk brown hair 4 3 yrs, want to go back 2 dark brown, howd i kno it will ok?

heya i hav realy realy dark brown hair, n dark brown eyes, n 4 the last 3 yrs i've had blonde highlights, my hairs looked really nice, but i want a change. I feel like i should go back 2 my natural coulour, or dye my hair dark dark brown, casa now i'm getin older i wana look older, n as i hav brown eyes i think brown hair would bring out ma eyes more. A girl in one of my classes, did have blonde hair, but recently dyed it mega dark brown, and it looks lush, really brings out her brown eyes, i'm hoping that this will happen 2 my hair, but is there any way i can find out 2 b sure? Because i dont want to make a mistake and then wait ages for it to grow out! thanks! xxxxxxxxxxx