Table has 14 GB in unused space - How to shrink table size
Whether a heap or a clustered index, you should find that you will be able to reclaim space in a table by rebuilding:

ALTER INDEX ALL ON dbo.myTableName REBUILD;


Note that reclaiming space in a table, and shrinking a database, are two completely separate things. Shrinking a database should be an exceptional thing - don't shrink a database just to free up disk space, since in most cases, the database will just have to grow and use that space again anyway.

As for determining how the table is distributed, sp_spaceused is pretty useless, since it just gives you a single line item with all data. First, check to see if your table is partitioned. You can see this quickly using:

SELECT COUNT(*)
  FROM sys.partitions
  WHERE partition_number &gt; 1
  AND object_id = OBJECT_ID(N'dbo.myTableName');


Next, see how the data is laid out across your seven indexes. If one of these is a lot bigger than it should be, you could try dropping/re-creating (including potentially removing, say, your XML column from the INCLUDE list), as there may be cases where LOB space for rows you've deleted or set to NULL doesn't get fully recovered, even after a rebuild.

 ;WITH x AS
  ( 
    SELECT i.name, type = pa.allocation_unit_type_desc, kb = COUNT(*) * 8
    FROM sys.indexes AS i
    CROSS APPLY sys.dm_db_database_page_allocations(DB_ID(), i.object_id, i.index_id, 
      NULL, 'LIMITED') AS pa
    WHERE i.[object_id] = OBJECT_ID(N'dbo.myTableName')
    GROUP BY GROUPING SETS((), (i.name, pa.allocation_unit_type_desc))
  )
  SELECT name, type, kb, 
    [%] = CONVERT(decimal(5,2), kb*100.0/(SELECT kb FROM x WHERE name IS NULL))
    FROM x
    WHERE name IS NOT NULL
    ORDER BY name, type;


If you want to see individual row sizes in the base table, you could do:

SELECT TOP (100) key, rowsize = DATALENGTH(col1) + DATALENGTH(col2) + ...
  FROM dbo.myTableName
  ORDER BY rowsize DESC;


If you have some that are quite large, you might want to make sure you need that data (otherwise set it to NULL, as it may be what's contributing to your size.