Most all pikes have some form of markings that differentiate the sexes.
In the wallaci and saxatiline groups, females do posses oceli in their dorsals. Many are irregularly shaped and some not well defined but they are there. Your fish indeed is a female. The round belly that is taking on a pinkish hue is another clue.
In the lugubris group, females develop a white submarginal band along their dorsal.
The reticulata group females develop red markins in their dorsal fins, and oft times on their bodies, but only when ready to breed. Otherwise many look just like the males.