I keep losing space on my hard drive on Mac

[zlloyd1]

I have a MacBook Pro laptop that is running High Sierra 10.13.4, and frequently I check my hard drive space available, and it has another several GB of unknown space used up that is nothing that I did....
There is no possible chance that it was me because I check my Email every morning before I go to work, and also check the free space on my drive, which I did this morning, but when I come home from work, having not touched the computer all day long, there is somehow 6 - 8gb less space on my drive. Can anyone tell me what could be causing this please??
Thanks in advance!!

 

[mrmez]

Apple logo (top left) -> about this mac -> storage -> manage.
Should give you a detailed list of whats there