The miraculous context is the future prophetic context and "Immanuel" in that context refers to its meaning, "God with us," which is a description of Messiah.
"Context" means "within the text". Outside sources such as the New Testament are not context. Even if they correctly explicate the text, they are not context.
So your unwarrented and unreasonable rejection of the miraculous....
I'm not rejecting the miraculous. I'm just pointing out what context means. You're welcome to use the New Testament to formulate your view of the Old Testament. You're also welcome to use C.S. Lewis or the funny papers. You just can't call them context.