the below script can help you to see and anlalyze that which tables and indexes which are taking huge space so that you can easily check where the actual space consumption

for table http://www.develop-one.net/blog/2011/06/20/SQLServerGettingTableSizeForAllTables.aspx

and for indexes

SELECT

i.name AS IndexName,

SUM(s.used_page_count) * 8 AS IndexSizeKB

FROM sys.dm_db_partition_stats AS s

JOIN sys.indexes AS i

ON s.[object_id] = i.[object_id] AND s.index_id = i.index_id

WHERE s.[object_id] = object_id('dbo.TableName')

GROUP BY i.name

ORDER BY i.name

SELECT

i.name AS IndexName,

SUM(page_count * 8) AS IndexSizeKB

FROM sys.dm_db_index_physical_stats(

db_id(), object_id('dbo.TableName'), NULL, NULL, 'DETAILED') AS s

JOIN sys.indexes AS i

ON s.[object_id] = i.[object_id] AND s.index_id = i.index_id

GROUP BY i.name

ORDER BY i.name