Electric field question?

Let the distance btw the 2 point charges=d m,the electric force felt by +Q produced by -Q obey an inverse square law: F=|+Q(-Q)|/(4pi(e)d^2)).the concept of using a unit +ve test charge to determine the electric field strength at a point is theoretically acceptable though a unit +ve test charge does not exist practically.field strength (E)=electric force felt by +1C at the point midway.this distance=d/2.with +1C placed at d/2,it feels an electric force=E=+Q/4pi e(d/2)^2.simplifing, E=+Q/pi e d^2,which is repulsive or -Q/pi e d^2 which is attractive when +1C is placed at d/2 m away from a -ve point charge. e=absolute pemitivity