How would something like this work in reverse. The situation doesn't work for me, can I just go back, magically?

It would depend on the individual case. Some multiple/plural systems can never integrate, some can. I think I could, if I wished to, but I would regard it as a loss rather than a gain.

This might be something to look into later in life, but having just come out of puberty maybe it would be better to deal with just Laura right now. *hugs self*

That may be a wise choice, then. Get to know what you want first, before you begin building it.