You might want to try using a clear acrylic sealant spray. I've personally used Krylon but really any brand that claims its food safe should do once fully cured. Make sure to apply it in a well ventilated area (preferably outside) and give it ample drying time between coats. That should give your stickers a nice protective layer while still allowing you to use the bottle for drinking. Good luck this really does sound like a nice conversation piece lol