Too dense with big holes?

 

Hi all, After many attempts I now better seek some help. I have been baking all my own breads for more than ten years and a couple of years ago I wanted to have a go at sourdough and bought Dan Lepards book 'The Handmade Loaf', and I followed he's recipe for a starter and everything went well. So after a couple of weeks when the starter seemed to look like the pictures in his book I followed his instructions on a white loaf. The loaf come out as quit dense with some very big holes. The flavour was nice as I had expected a sourdough bread to taste, but I wasn't satisfied with how dense it was, so I tried another couple of times with the same disappointing result.So I left it for a couple of month and then I bought another book, Tatine Bread, and followed the directions in this book, but I still ended up with a very dense loaf with big holes.I simply cannot figure out what I do wrong, as I have followed both recipes to the letter.Any suggestions what I do wrong? Many thanks in advance. Happy bakingJan