It seems that you have reduced the size too much.
In short, from one of the convolutions onwards your feature map is already smaller than 3x3 (the kernel size). In fact 1x1 (so it’s not even 2d but a vector)
Use a bigger input image or delete some convolutions
By default VGG images are 112x112 if i’m not wrong (so that is the optimal size for the pretrained wiegths)