Detecting collision of two game objects?

So I have an object with a collider attached to it and I made two colliders attached to the main camera (to stop the player from walking beyond the main camera boundaries) now I have a condition where the camera stops following the player when a certain object is on the screen and touching the collider on the left of the screen which is in this case the left boundary but I can't get to make this work I used this code:

 public class leftWallCheck : MonoBehaviour {
 
     private baby baby;
     // Use this for initialization
     void Start () 
     {
         baby = GameObject.FindGameObjectWithTag("Baby").GetComponent<baby>();
     }
 
     void OnCollisionEnter2D(Collision  col)
     {
         if(col.gameObject.tag == "Baby")
         {
             Debug.Log(baby.touchLeftWall.ToString());
             baby.touchLeftWall = true;
         }
     }
 
     void OnCollisionStay2D(Collision col)
     {
         if (col.gameObject.tag == "Baby")
         {
             Debug.Log(baby.touchLeftWall.ToString());
             baby.touchLeftWall = true;
         }
     }
 
     void OnCollisionExit2D(Collision col)
     {
         if (col.gameObject.tag == "Baby")
         {
             Debug.Log(baby.touchLeftWall.ToString());
             baby.touchLeftWall = false;
         }
     }
 
 }
 

this code attached to the left wall and "Baby" is the object I want the left wall to detect, but it is not working and the value of "touchLeftWall" is not changing