OP, you are a light rider, running good tire pressure on a fairly new bike. Your commute is on fairly decent roads and isn't epic in terms of distance. Once those wheels were trued by your LBS, they should have stayed that way for quite a while. Something is missing here.
When the wheel was first trued was it actually damaged?
A wheel can go out of true for 2 reasons: 1. Spoke tension or, 2: A bent rim. If your spoke tension was off (which happens to almost every new bike during the brake-in period) then re-tensioning the spokes should have done the trick. If the rim was actually bent, then you can true it back into shape (sort of) but then it will continually go out of true - the damage has been done.
I would stop off at your LBS and ask them if the rim itself has been damaged. If so, you will need to replace it.