About a week ago I made a starter using 2oz rye flour + 2oz water (discarding half and feeding same quantities daily), which started to show bubbles under the surface  and rise after 4 days.  Over the past 3 days since then I've introduced a percentage of white flour when discarding half and for the past 2 days the starter has doubled in size over a few hours.  I took this to mean it was ready to use, so tried making the basic sourdough from Emmanuel Hadjiandreou's How to Make Bread book today (I'd tried making his starter but had no joy, though his seemed to still use equal quanitites of flour and water).

I followed every step of the recipe faithfully, but even though I left the dough for longer than suggested - 8 hours, it barely rose at all.  It looked very "wobbly" under the surface when I turned it out of the banneton and as soon as I even slightly touched it with a knife, it deflated and went flatter than it was already.

I thought that maybe it would gain some oven spring, so went ahead and baked it, using a pre-heated baking stone, the cup of water in a tin at the bottom and spraying water onto the walls of the oven too.  Sadly for me, absolutely nothing happened and I ended up with a sourdough pancake about 1" high rather than anything that could be described as proper loaf of bread.

I'd be grateful to know where I went wrong, eg was I wrong to use my own starter in the recipe or is the starter doubling in size not an indication that it's ready to be used?  I fed the starter after I'd removed what I needed for the recipe and again it doubled in a few hours, so I've now put it in the fridge, under the impression that I can leave it there now and just refresh it once a week.  Am I even on the right track with that?

Many thanks!