Hi and welcome to HCm.
It is good to be caotious about childs health but hypochondria wont be helpful for you and her either.
Blood work is normal,slightly raised WBC
means nothing or some healed respratory infection.
These bruises would be rlated to trombocytes and clooting factors and these are normal so she probbaly just got hit and you didnt notice. Leukemia
is rare,you should visit doctor if you find something suspicous but spare your child of unnecessary blood testing everytime you notice fever
, bruise or cough
. Wish you good health.