Platformer Character

So I've been working on a little platformer, and I've been trying to set up custom physics for the player. It works fine, until I add the ability to run. He seems to be going faster than my physics can keep up with. He keeps going into walls and slopes. Any idea how I should fix it? Thanks!

 public float Y_Velocity;
 public float X_Velocity;
 private string dir;
 private bool jumpKey;
 public bool onGround;
 public LayerMask mask;

 void Start ()
 {
     
 }
 
 void FixedUpdate ()
 {
     transform.rotation = Quaternion.Euler(0, 0, 0);
     if (Input.GetKey("z") && Y_Velocity > 5.5f)
     {
         Y_Velocity = Y_Velocity - 0.5f;
     }
     else
     {
         Y_Velocity = Y_Velocity - 1;
     }        
     transform.Translate(Vector3.up * Time.deltaTime * Y_Velocity);
     if (!Physics2D.Raycast(transform.position + new Vector3(-0.2f, -1f, 0), Vector3.right, 0.4f, mask))
     {
         onGround = false;
     }
     if (Y_Velocity > 0)
     {
         while (Physics2D.Raycast(transform.position + new Vector3(-0.2f, 0.55f, 0), Vector3.right, 0.4f, mask))
         {
             Y_Velocity = 0;
             transform.Translate(Vector3.down * Time.deltaTime);
         }
     }
     if (Y_Velocity < 0)
     {
         while (Physics2D.Raycast(transform.position + new Vector3(-0.2f, -0.55f, 0), Vector3.right, 0.4f, mask))
         {
             Y_Velocity = 0;
             transform.Translate(Vector3.up * Time.deltaTime);
             onGround = true;
         }
     }
     if (Input.GetKey("z") && jumpKey == false && Physics2D.Raycast(transform.position + new Vector3(-0.2f, -0.65f, 0), Vector3.right, 0.4f, mask))
     {
         Y_Velocity = 15;
         jumpKey = true;
     }
     X_Velocity = X_Velocity * 0.7f;
     transform.Translate(Vector3.right * Time.deltaTime * X_Velocity * 3);
     if (Input.GetKey("right"))
     {
         if (Input.GetKey("a"))
         {
             X_Velocity = X_Velocity + 1;
         }
         X_Velocity = X_Velocity + 1;
         dir = "right";
     }
     else if (Input.GetKey("left"))
     {
         if (Input.GetKey("a"))
         {
             X_Velocity = X_Velocity - 1;
         }
         X_Velocity = X_Velocity - 1;
         dir = "left";
     }
     if (X_Velocity > 0)
     {
         while (Physics2D.Raycast(transform.position + new Vector3(0.25f, 0.55f, 0), Vector3.down, 0.9f, mask))
         {
             X_Velocity = 0;
             transform.Translate(new Vector3(-0.1f, 0, 0) * Time.deltaTime);
         }
     }
     if (X_Velocity < 0)
     {
         while (Physics2D.Raycast(transform.position + new Vector3(-0.25f, 0.55f, 0), Vector3.down, 0.9f, mask))
         {
             X_Velocity = 0;
             transform.Translate(new Vector3(0.1f, 0, 0) * Time.deltaTime);
         }
     }
     if (dir == "left")
     {
         transform.rotation = Quaternion.Euler(0, 180, 0);
     }
     if(!Input.GetKey("z"))
     {
         jumpKey = false;
     }
 }