It appears that your movement dice and Command dice let you down,
I won my Perbais game in the second turn using a MC Recce Squad, a SNT, a PGB and a 75mm LeIG. I found the extra deployment for the Recce Squad pushed them well forward but they eventually were stymied by losses and had to remain in the wheat field taking more fire while the LeIG was able to pound an MMG that the French had taken. I used a fresh platoon as the first took a lot of casualties in round 1.