Your tongue looks fairly healthy, the only things that stand out are the teethmarks on the edge (SP Qi Deficiency), possibly the crack in the ST/SP area although that is not very pronounced and the wetness (which I cannot see from the picture - and that sounds mild as well). All together, the tongue shows some spleen qi deficiency, possibly yang deficiency. This can be from over eating, poor sleep, not enough movement, recovering from an illness - just about anything that weakens the body.
It is important to note, however, that you never take an individual sign such as the tongue as the only indicator for imbalance. Properly done, the diagnosis would involve the tongue, pulse, palpatory diagnosis, and your other signs and symptoms.