In the enchanting table i can only get level one enchantments

When trying to enchant a tool i have only been able to get level one enchantments, even when i enchant the item, grindstone it, and try again, i'm only able to get efficiency one, unbreaking one, etc. this has happened for the last i'd say 8 or so cycles of enchanting and then grindstoning it and then enchanting again. Either this is really bad luck or a bug and i'm gonna say it's a bug. Please look into this, Thanks!