You didn't mention any details about the symptoms which made you visit the hospital.
There are definite blood tests which can accurately diagnose whether you have leukemia and it belongs to which type.
The leukemias which occur in your age group are having fairly good outcome after proper therapy.
I'd advice you to perform a complete blood count
, peripheral blood smear examination, also a lymph node biopsy
or bone marrow
study with immunohistochemistry
. These will help you to reach a definite diagnosis.