I am suffering anxiety I feel extremely fatigue, pounding heart and shaking legs, even when I am not very anxious also I face these problems?

Anxiety. Recommend seeing your primary care doctor for workup to rule out physical causes of anxiety, and referral to a psychiatrist for treatment.
A little goes far. You likely are underestimating the severity of your illness. Anxiety takes a toll on the body both emotionally and somatically. In addition to neuronal overstimulation followed by transmitter depletion, are sleep disorders, nutritional problems, physical deconditioning. Have a general medical evaluation. If nothing shows up, consult your psychiatrist for additional treatment.