Usually a compact is required to recover space after deleting documents. However, since you said the document count hasn’t changed, take a look at the last tab on the database properties box. Is the “Allow soft deletions” box checked? If so, you will also see a box that indicates how many hours it will be from the time a document is deleted to the time it is actually removed. After that time has passed, a compact will recover the space. Or, you can uncheck the box for soft deletions.