i think you were penalised by getting 20% possession ..if you could use 4 defenders instead of that 3 then you could easily win..
4-1-2-1-2 narrow diamond was a better idea instead of 3-1-3-1-2...Some months ago,i faced an opponent with 3-1-3-1-2 and i used 4-1-2-1-2 and he was penalised by 20% and i won 3-0..Good Luck!