The Missy the Werecat Series: Volumes I, II & III by P. G. Allison

Vol I - Forced to Shift, she lives as a mountain lion for two years before learning to Change back; she then keeps her werecat nature a secret.  Vol II - With help from the FBI, she copes with crime bosses while finishing high school and starting out at West Point.  Vol III - Can Missy somehow provide assistance during an international crisis?