I'm with Virgo. 2 Bedder on 42sqm is tough. You have 18sqm less than 'standard' 60 sqm gf. That 18 sqm is equivalent to a large 4 x 4.5 sqm room! I would have gone for max size at any cost. Is it the covered concrete restricted the buildable size?
I thought the back setback needs to be around...