Blank pages can also be created because what is called to be there won't fit.
It might be invisible.
Top and bottom margins and/or padding that are part of pictures or text.
I avoid bottom margins on text blocks, just because of this. You see the text right where you want it (it is right at the bottom of the screen), but you get a blank page because there was no room for the Bottom Margin. So, I just use the TOP margin to space the next P (any block item) down.
If this is the case, Using the Text size SMALLER on the reading device, may make the blank go away because the screen full, now fits
a CSS page_break_before(after): always assigned to the Starting (first) blocks class ("p2" OR "t26" in your case)
You need to add up the vertical margins and padding for the entire body in this case (single page).
Lucky for you, the calibre Editor includes the "Inspector" tool that can displa the current metrics for the selected block. (choose each nested block, and see whats going on an in the right pane). Remember the first C in CSS is Cascade. Your margin numbers may be accumulating.