How to know my workload type
You can use the information available in sys.dm_db_index_usage_stats for that purpose. The following query returns the number of reads and the number of writes against each database since the last server restart. That information is stored in memory only and therefore not preserved past a server restart. 

SELECT D.name AS database_name, D.state_desc,D.is_read_only,X.read_cnt, X.write_cnt
  FROM sys.databases AS D
  LEFT JOIN(
       SELECT database_id,
              SUM(DDIUS.user_seeks+DDIUS.user_scans) AS read_cnt, 
              SUM(DDIUS.user_updates) AS write_cnt 
         FROM sys.dm_db_index_usage_stats AS DDIUS
        GROUP BY DDIUS.database_id
      )X
    ON D.database_id = X.database_id
 ORDER BY database_name;


The numbers represent the count of "actions" against the tables in a database. You cannot judge the amount of data read or written based on these counts. The DMV also includes a user_lookups column. I did not include those, as a lookup usually implies another read action. For example a single index scan can cause thousands of lookups. But it still is only a single read action.