iTunes will only list 6 of 8 of my podcast episodes. When I had only 7 episodes, iTunes still only listed 6 of them. It seems every time I list a new episode, iTunes removes 1 to still only list 6 of them.
Three of your episodes have the same 'guid' tag: iTunes uses these to confirm that each episode is separate and will ignore any episode which repeats the tag. Furthermore in the bottom episode the guid tag says 'permalink=true' and as it isn't a URL it should say 'false'.