iPhone Storage Full, can't clear it

Hello! For the last week or two my iPhone (6S) has been saying that storage is full. I deleted apps, videos, pictures, etc. Deleted large attachments on messenger and cleared my WhatsApp chats. Under settings it says that the majority of my space is being used by "other." I've dug around online and have followed suggestions to delete safari Caches, etc. but it's not working. I currently have very very few apps, but I'm really frustrated because I can't even open WhatsApp which I depend on for work as well. I don't know what else to do. Please help!!!