Increasing possession in a successful tactic

[nick1408]

Bit of a funny question this one as I want to change a successful tactic. I am currently playing this:

It's been really successful. I won a Bundesliga with Leipzig and overachieved in LaLiga with Real Sociedad (3rd and 4th). My issue is I only get around 35% possession. I know this setup won't garner a lot of possession but I would like to raise it to around 45%. I've tried shorter passing but besides that I'm not really sure what the next step would be.

 

Thanks in advance for advice.