I can understand why you are scared - leukemia is a very scary word. Basicaslly, leukemia is a form of cancer that affects your white blood cells, causing them to grow abnormally and crowd out your normal healthy blood cells such as red blood cells and platelets (which control blood clotting).
Leukemia van cause a number of symptoms including Fevers, night sweats, frequent infections, feeling weak or tired, headache
Bleeding and bruising easily (bleeding gums, purplish patches in the skin, or tiny red spots under the skin)
Pain in the bones or joints
Swelling or pain in the abdomen (from an enlarged spleen)
Swollen lymph glands in the neck or armpit, and weight loss
If your doctor suspects leukemia, he may refer you to an oncologist (cancer doctor) or hematologist (doctor who specializes in blood diseases) for further tests, which might include blood tests, a bone marrow biopsy or needle aspiration, chest x-ray and CT scans. There are several diffent types of leukemia, so treatment depends of the type and severity of the diserase.
There are many diseases which can cause some of the same symptoms as leukemia, so try not to be too worried until your doctor makes a definite diagnosis. I hope your doctor has an answer for you soon - waiting is a scary and frustrating thing