Larger image after wavelet reconstruction Depending on the size of the original image and depending on the kind of padding used during 2D discrete wavelet transform and reconstruction, the reconstructed image has a larger size.

Is there a general method given a mxn matrix and given some padding mode to crop the obtained pxq matrix to the mxn matrix (without trying every possibility in order to find the one with the least error)?
A generic method consists in adapting the wavelet decomposition on the border, ie the wavelet varies on shorter frames. It can be called "wavelet on the interval" or be addressed with lifting schemes. But this requires caution and complicated computations sometimes. 

A more lazy option (if I remember well)  is to use a pair of symmetric/anti-symmetric $M$-band wavelets, over $J$ levels. If you expand the image to a size that can be divided by $J^M$ (the most symmetrically as you can), and use  a symmetric extension that may reveal non-expansive if properly tuned. This may vary with implementations.