Is this consider a room ?

[Juan M Restrepo]

Hello guys, Newbie investor here. I have a house that rents around $1500 a mount as a 3 bedroom 2 bathroom house. The house actually has another room that is not shown on realtor.com or any Real State website. Is an attic room so the walls are slanted. The room has a window, a door and a open closet. I live in the state of Georgia (Hall county). I was wondering if I  could count this as another room? The rents for my property in rentometer for a 4 bedroom, 2 bath are around $1700. I read somewhere that the ceiling need it to be at least 7 feet to be consider a room and I do not know if the slated walls violate that or the open closet. 

Here is a picture:

Thank you guys for the help.