Are all lone pairs considered as π-electrons?
I am quoting from http://www.hutters-online.de/publikationen/dmchdo.html.


  One requirement that is basic to this concept and is agreed upon by most authors is that there have to be two double bonds that are in conjugation with a third one, but not in a linear arrangement. The p electronic system thus forms a bifurcation. So the simplest cross-conjugated hydrocarbon would be 3-methylene-1,4-pentadiene (I) that can be viewed as an ethene disubstituted geminally with two vinyl groups:


Based on the above the following resonance structures are possible. These have 8 $\pi$ electrons in conjugation. You are correct.