You can calculate the Left property like this:
Private Width As Int
Width = (DotRadius * 2 + DotsSpacing) * NumberOfDots - DotsSpacing
dots.Left = (100%x - Width) / 2
Unfortunately the Width property returned by the library is the width from the Designer and not the real width.
And DotRadius, DotsSpacing and NumberOfDots are write only so you need to enter your values or define variables for them.
You should use dip values for DotRadius and DotsSpacing and not pixel values!