Extreme nail biting issue?

I've got a really bad nail biting habit. I've tried getting a manicure to make them look nice and not want to bite them, I've tried the bitter, clear nail polish that's supposed to make you stop biting them, if I chew gum one more time in school I'll get a detention and I don't want that, I've grown out of my habits of trying to bite pencils as a substitute, one time I actually stuck tape around my nails to get me to stop (but the tape got all dirty around the edges and it was gross) None of these ideas worked. I don't have anxiety issues, I just hate sitting still so I bite my nails and once you get into a habit it's too hard to stop. There is no motivation like "ooh my nails are gonna look so pretty if I don't bite them" because all I can think is "oh my gosh I NEED to bite my nails!!" Is there like a pill I could take to stop myself from biting my nails or something? Thank you so much for all of your help!!