How to instantiate tiles based on a 2D Array into a Platform Game?

I'm building a very simple platform game using 2D array to build the map based on it.

There are two simple goals I want and I'm currently not finding the answer:

1. Ensure that the camera is 16:9 and my scene will be 100% displayed in it

2. Build a 2D platform tileset as in an array

My environment:

• Unity 5.5.0f3 (in 2D Mode)

• Camera projection ortographic size 10.9

• Game displayed in 16:9

• Tileset dimensions are 128x128 px

Here is my current code:

 public Camera camera;
 public GameObject prefab;
 
 void Start () {
     Vector3 pos = camera.ScreenToWorldPoint(new Vector3 (0, 0, 0));
     Vector3 nextPosition = pos;
     for (int i = 0; i < 32; i++)
     {
         for(int j=0; j < 18; j++)
         {
             GameObject a = Instantiate(prefab, new Vector3(nextPosition.x, nextPosition.y, 0), Quaternion.identity);
             nextPosition = new Vector3(pos.x+(prefab.GetComponent<Renderer>().bounds.size.x)*i, pos.y+(prefab.GetComponent<Renderer>().bounds.size.y)*j,0);
         }
     }
 }

There are 3 things to notice about it:

• I'm using ScreenToWorldPoint to get me the position for 0,0,0

• My building order goes from bottom left to top right, each iteration is put as the past position + block width/height (x and y)

• I'm using a 16:9 for scheme which is 32:18

Using it, this is my result:

As you can see it stays out of the camera boundary and even tho both camera and code are 16:9, it exceeds 1 column. Also note that the instantiate point is exactly in the middle of my GameObject, so I start instantiating it as half of the gameObject's width and height, meaning:

 Vector3 pos = camera.ScreenToWorldPoint(new Vector3 (64, 64, 0));

And the reuslt is the following:

Not what I expected at all, by trial and error I figured out it is suposed to be at 16,16:

 Vector3 pos = camera.ScreenToWorldPoint(new Vector3 (16, 16, 0));

Now its a perfect fit, but it exceeds 1 line at the top and 1,5 columns at the right. Which shouldn't because they are both 16:9

I'm clearly doing something wrong but I can't see what, I've been through this problem in the past but I don't remember what I figured out.