It looks that what I was needing, was a lunch break ... 🙂 ...

Got the solution myself. Posting in case someone else is looking for the same ...

SELECTSD.name,

MF.database_id,

CONVERT(decimal(10,2),(DF.size/128.0)) AS CurrentSizeMB,

CONVERT(decimal(10,2), (CAST(FILEPROPERTY(DF.name, 'SpaceUsed') AS INT)/128.0 ) ) AS UsedSpaceMB

FROM sys.master_files MF JOIN sys.databases SD

ON SD.database_id = MF.database_id

JOIN sys.database_files DF

ON DF.physical_name = MF.physical_name

WHERE MF.type = 0

This T-SQL code will provide a result set with: database name, database ID, Current Size and Used Space ...

Cheers ...