My raycast wont function properly

Hi folks, Relatively new Unity dev here with a quick Question. The goal of this function is to fire a raycast sequentially from 1. The center of the 3D object 2. Both sides of the object on the y axis 3. Both sides of the object on the x axis

If these rays intersect with another object with a collider (e.g any object they could jump or walk on), the function flips a switch(bool) to say if the 3D object is grounded or not. This enables me to code different behavior into the different states. The code works if i remove steps 2 and 3, but it fails to flip the switch when the objects center (transform.position) is hanging over the edge of the object in question. I'd like it to function properly to keep responsiveness and quickness in my jumps.

Here is the code

   bool IsGrounded () // Checks if the object is on the ground
             {
             float _spriteDimensionX = 0.4f;
             float _spriteDimensionY = 0.4f;
             if(Physics.Raycast (transform.position , - Vector3.up, GroundDistance + 0.51f)==true)
             {
                 Debug.Log ("MID");
                 return true;
             }
             else if (Physics.Raycast (transform.position + new Vector3 (_spriteDimensionX , 0.0f, 0.0f) , -Vector3.up, 0.5f)==true)
             {
                 Debug.Log("X");
                 return true;
             }
             else if (Physics.Raycast (transform.position+ new Vector3 (-_spriteDimensionX, 0.0f, 0.0f), -Vector3.up,0.5f)==true)
             {
                 Debug.Log ("-X");
                 return true;
             }
             else if (Physics.Raycast (transform.position+ new Vector3 (0.0f, _spriteDimensionY, 0.0f), -Vector3.up,0.5f)==true)
             {
                 Debug.Log ("Y");
                 return true;
             }
             else if (Physics.Raycast (transform.position+ new Vector3 (0.0f, -_spriteDimensionY, 0.0f), -Vector3.up, 0.5f)==true)
             {
                 Debug.Log ("-Y");
                 return true;
             }
     
             else return false;
             }