Thank you for the support, everyone, and sorry if I seem a bit lethargic. It's just that I feel paralyzed. RazorChain mentioned "nagging feeling" and that is something that I have as well, including constant terror.

Factotum's comment "So long as your students can be understood when speaking English then I would call that a good job on your behalf" got me thinking. I'm not trying to work miracles here. I'm just helping them to improve their English from X to X+1. And X will never be "native fluency". Not even close.

If you would like to, we could share experiences and even brainstorm some ideas, unite our power and stuff
I would like that, very much, and I'm glad that someone in the same situation read my post. Would it be too much if I sent you my Skype username via PM?