Quantization Problem...Help Please

if your input is 11 bits and output is 34 bits then you have allowed full bit growth to appear out and so will appear scaled up a lot. At the output you need to truncate off some LSBs and possibly discard some MSbs plus saturation. The number of LSBs to be discarded depends on how you scale your coeffs (decimal point) so discard as many as decimal point. I assume your tool is supposed to do that because you define 'nearest' etc. but your output size should be 11 bits if you want to compare input with output