Tummy tuck
By two years after surgery, there shouldn't be swelling. If there is a fluctuation in swelling, do you notice it anywhere else, like your hands or feet? If so, that could be related to generalized shifts in swelling like everyone could get with too much salt or alcohol intake or with hormonal changes. If there is permanent swelling, then it is probably an increase in fat in the area. Check your weight compared to the time of surgery and consult with your original surgeon to get the most accurate feedback.
You did not discuss any specifics or post photos. However, after 2 years from surgery, your swelling is not from the tummy tuck. I suggest you be checked for food allergies. You may be swelling from this.