There are smaller 9mms that could be pocket carried easier than the one you have. Perhaps the Kahr PM9 would work a little better for you. I prefer pocket carry over IWB personally, so I carry an LCP most of the time, with practice you should be able to empty a mag center mass, that should do the job.
Maybe a tuckable IWB holster so you can carry the pistol with your dress shirt tucked in, and then the white jacket over the top.
Or you could just say "My Grandfather lived to be 98 years old". And then when your co worker asks you what that has to do with it, say "He knew how to mind his own damn business".