TouchCount always > 0 on Android

I'm working with Unity/Android for the first time. I have several objects on the screen all with the same script on each. I want to be able to independently drag each object around. This works fine when I test it in the game tab, but when I actually build on Android it doesn't work correctly. Instead, after touching an object once, anytime I touch the screen anywhere else it instantly jumps there. Not just when I drag. Could anyone tell me what i'm doing wrong (and maybe a few other tips? I know the way i'm doing this isn't the best...)

 using UnityEngine;
 using System.Collections;
 
 
 public class handleTouch : MonoBehaviour {
 
     // Use this for initialization
     void Start () {
     
     }
     
     // Update is called once per frame
 
     public bool dragging = false;
     void Update()
     {
         var aTouch = Input.GetMouseButton(0);
         var touchPos3D = Input.mousePosition;
         var firstTouch = false;
 
         if (Application.platform != RuntimePlatform.IPhonePlayer && Application.platform != RuntimePlatform.Android)
             
         {
             if (Input.GetMouseButtonDown(0)){
                 firstTouch = true;
             }
         } 
         else 
         {
             aTouch = (Input.touchCount > 0);
             touchPos3D = Input.touches[0].position;
 
             if (Input.touches[0].phase != TouchPhase.Moved){
                 firstTouch = true;
             }
         }
 
         if (aTouch)
         {
             Vector3 wp = Camera.main.ScreenToWorldPoint(touchPos3D);
             Vector2 touchPos2D = new Vector2(wp.x, wp.y);
 
             
             if (this.collider2D == Physics2D.OverlapPoint(touchPos2D) && firstTouch == true)
             {
                 dragging = true;
             }
             else
             {
                 if (dragging == true)
                 {
                     this.transform.position = touchPos2D;
                 }
             }
         }
         else
         {
             dragging = false;
         }
     }
 }