Did you take the wheel back to the shop and have them "RETENSION" the wheel?
Many times the wheel will lose tension after a break in period (200-300 miles) and needs to be readjusted. If the shop only trued the wheel, then they are not all that competent.
Truing a wheel only straightens the wheel. Tension keeps it from going out of true.
At your weight, you shouldn't have any problem with a decent MTB wheel.