Preparing a query to paste into excel to get growth by month
Well I could crate a dynamic pivot. Maybe it can help you guys with your own tasks someday:

DECLARE @cols AS NVARCHAR(MAX),
        @query  AS NVARCHAR(MAX)

select @cols = STUFF((SELECT ',' + QUOTENAME(name) 
                    from TblDataBaseSize
                    group by name
                    order by name
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')

set @query = 'SELECT date,' + @cols + ' from 
             (
                select month(date) as date, name, convert(int,data_size_mb) as data_size_mb
                from TblDataBaseSize
            ) x
            pivot 
            (
                avg(data_size_mb)
                for name in (' + @cols + ')
            ) p '

execute(@query);


The reason that i needed to create the dynamic is because I dont know how many databases I will have. This one above will create for a fixed numbers of databases ( or something different ).

select *
from 
(
  select name, month(date) as mes, data_size_mb
  from TblDataBaseSize where name not in ('master','model','msdb','tempdb')
) src
pivot
(
  avg(data_size_mb)
  for name in (
[DB1], [DB2]    ,[DB3]  ,[DB4]  ,[DB5] ...
)

) piv;


I must say it didn't help me with anything because excel still cant understand what I need haha but it was a cool challenge.