Triangulation from set of points from left camera
You don't need to estimate points in the second image, you need to match them.  

One way is to take a patch of pixels around the point in one image and see which of the points in the second image has a patch most "alike".  One very simple way to do this is to take the sum of the squares of the difference between each pixel in the left-patch and the corresponding pixel in the right-patch.