The bacpac file is going to be significantly smaller than the DB as it's a compressed version of the data and I believe it strips out things like index content and only stores index definitions which are reindexed on restore so one shouldn't be indicative of the other.
For example, I have a database on SQL Azure configured as a 10GB Premium DB, which is currently using 2.7GB, which BACPACs to about 300MB
What kind of database have you configured ?
What Edition, Size and Usage settings are you currently being shown.
** Edit ** Image wasn't loading so here's the external link - http://i.snag.gy/JfsPk.jpg
The next thing to check is the size breakdown in the database by table/object.
Connect to your Azure environment with Management Studio and run the following query. which will give a table breakdown of the database with sizes in MB.
select
sys.objects.name, sum(reserved_page_count) * 8.0 / 1024
from
sys.dm_db_partition_stats, sys.objects
where
sys.dm_db_partition_stats.object_id = sys.objects.object_id
group by sys.objects.name