It might be really lacking in body. Next time this happens, don't give up on the wort. You can try steeping the grain bags again at 150-155F for an hour to an hour and a half more. If you're still unsatisfied with the gravity, or pressed for time, add a pound of honey during the boil. It ferments almost completely and leaves no off-flavors.
Another tip - use multiple grain bags. I'm not sure how many you used, but I usually use four and do two separate mashings. Using too few grain bags can cause grains in the middle of the bag to be nearly untouched by the water and therefore wasted.