Using LocationTextExtractionStrategy in itextSharp for text coordinate
Its very important to understand that PDFs have no support for tables. Anything that looks like a table is really just a bunch of text placed at specific locations over a background of lines. This is very important and you need to keep this in mind as you work on this.
That said, you need to subclass TextExtractionStrategy and pass that into GetTextFromPage(). See this post for a simple example of that. Then see this post for a more complex example of subclassing. The latter isn't completely relevant to your goal but it does show some more complex things that you can do.