Couple of tips: you can put Raketenwerfers (the AT gun) into buildings, it makes them easier and faster to track down targets even if they leave the initial shooting cone.
And the other one is about the Luchs, which would have been the ultimate unit you should have built to easily take out those M3s (and accessible way before the JPIV): your BO already included 2 AT guns and 3 schrecks, the JPIV was a bit overkill (i'm not saying it was a mistake but just that the Panzer II Luchs would have been ideally better in that situation).
For the rest WP, you did the right things
![:) :)](/images/Smileys/smile.gif)