You did not build tier one until 11 mins into the game, never do that. You opponent was also pretty bad, and if he had built 2-3 more riffles it would have been gg by the 7min mark. Build tier one for Ostheer, even if you are not going to use it you will need it. One last thing, since you were only using pios in the beginning, you should have built about 4 more and you would have most of the map control.
Also medic halftracks for Ostheer can only be deployed in your base sector.