Database size 1T but unclear why

Hi,
I'm trying to understand why my database consume so much space. I checked
the space it consume on disk :

[root@ base]# du -sh * | sort -n
1.1T 17312
5.2G pgsql_tmp
6.3M 1
6.3M 12865
6.4M 12870
119G 17313

myBIGdb=# select t1.oid,t1.datname AS
db_name,pg_size_pretty(pg_database_size(t1.datname)) as db_size from
pg_database t1 order by pg_database_size(t1.datname) desc
myBIGdb-# ;
oid | db_name | db_size
-------+----------------+---------
17312 | myBIGdb | 1054 GB
17313| mySmallDB | 118 GB
12870 | postgres | 6525 kB
1 | template1 | 6417 kB
12865 | template0 | 6409 kB
(5 rows)

However, when checking the sizes of my biggest tables (included with
indexes and toasts) :
select a.oid as oid a.relname as table_name,pg_relation_size(a.oid,
'main')/1024/1024 as main_MB,
pg_relation_size(a.oid, 'fsm')/1024/1024 as fsm_MB,
pg_relation_size(a.oid, 'vm')/1024/1024 as vm_MB,
pg_relation_size(a.oid, 'init')/1024/1024 as init_MB,
pg_table_size(a.oid)/1024/1024 AS relation_size_mb,
pg_indexes_size(a.oid)/1024/1024 as indexes_MB,
pg_total_relation_size(a.oid)/1024/1024 as total_size_MB
from pg_class a where relkind in ('r','t') order by
relation_size_mb desc,total_size_MB desc limit 10;

oid | table_name | main_mb | fsm_mb | vm_mb | init_mb |
relation_size_mb | indexes_mb | total_size_mb
------+-----------------------------+---------+--------+-------+---------+------------------+------------+---------------
*17610 *| table_1 | 1 | 0 | 0 | 0
| 115306 | 0 | 115306
17614 | *pg_toast_17610 *| 114025 | 28 | 0 | 0
| 114053 | 1250 | 115304
*17315 *| table_2 | 166 | 0 | 0 | 0
| 2414 | 18 | 2432
17321 | *pg_toast_17315 *| 2222 | 0 | 0 | 0
| 2223 | 24 | 2247
*17540* | table_3 | 1016 | 0 | 0 | 0
| 1368 | 1606 | 2975
17634 | table_4 | 628 | 0 | 0 | 0 |
677 | 261 | 938
17402 | table_5 | 623 | 0 | 0 | 0 |
623 | 419 | 1043
17648 | table_5 | 393 | 0 | 0 | 0 |
393 | 341 | 735
17548 | *pg_toast_17540 *| 347 | 0 | 0 | 0
| 347 | 4 | 351
17835 | table 6 | 109 | 0 | 0 | 0 |
109 | 71 | 181

As you can see , the sum of the biggest tables is under 200G. In addition,
I know that on that database there were some vacuum full operations that
failed. So is there an option of orphans files in case vacuum full failed ?
In addition, what else would you recommend to check to understand why the
database consume so much space ?

Thanks .