Solved by static_cat in post #3 
              
              
                Realized it was this code I needed to tinker with. Changed it to: 
        nn.AdaptiveMaxPool2d(output_size=6))
    self.fc = nn.Linear(in_features=1152, out_features=3)

And my train and test phases work successfullly! Only 77% accuracy, but I’ll see if I can improve it now.