When you put the SD card in the phone it will ask what you want to do with it, do you remember the prompt?
Check Settings > Storage and post a screen shot.
There are many topics on to this.
Once an SD card has been formatted as Internal, even thouigh removed and one being used as Portable you may see another mention
Meanwhile clear the camera cache and ensure you empty the ‘bin’ of deleted images etc.
Out of storage does not mean you have no space in the memory and you didn’t give any details.