Braces and Retainer?

I got my braces off about 3 months ago, and I have a permanent bottom retainer, and an invisible top retainer that I only wear at night. I have wore it every night, but recently I forgot it in my sports bag at school so I haven't had it. I didn't have it in Wednesday Night, Thursday Night, and now I forgot again (stressfull at school), and I have to go without it tonight. I am going back to school tomorrow to try and get it then, but I am really worried my teeth are going to move. Will they move to much before I can get my retainer back? I am really stressing out about this!!! And what if I can't get in the school tomorrow...then I can't get it back till Monday? I plan to wear it for a few days during the day, so that hopefully if they haved moved (and I know it will probably be painfull) that they will go back to where they were. Do you all think they will move after missing these couple of nights?