I am afraid I cannot recommend any English texts on Buddha Dhamma. They are all contaminated.
1. Are you certain that you have covered most of the material on this site? You may want to take a look at following sections:
“Living Dhamma”
2. Once one gets past the Sotapanna stage, the task is mainly to live life with Anapanasati/Satipatthana based on Tilakkhana:
“Anicca, Dukkha, Anatta”
3. In the following thread, there was a long discussion about how to proceed after the Sotapanna stage. Unfortunately, the title does not match the discussion, so it took me a while to find it:
“Vipassana Meditation”
– Read through to the end, and you may find useful information.