Carolyn,
I've been following your blog on my Google reader, thanks to a reference from Matador.com. It's been particularly interesting to me as an ex-pat living in a neighboring Eastern European country.
It occurred to me that there is one element that you haven't yet discussed regarding your quest for better Bulgarian skills: Willpower. 
In my quest to develop my language skills, I found that willpower was a crucial ingredient. That is, I had to have the willpower to insist on speaking the foreign language, even when my counterparts offered to speak English. 
You wrote that young people in Bulgaria crave opportunities to speak English. The same applies here. Unfortunately, this means that oftentimes we have conflicting goals. They want to speak English. I don't. And it becomes a matter of willpower to see which language will be the currency of these relationships. 
I have had to refuse to speak English, even when people have insisted that we speak it. I have felt selfish, guilty, and worse after flatly refusing to speak English. Promising acquaintances/relationships have petered out simply because I have refused to speak English. In the end, I have greatly improved my language skills. But it required A LOT of willpower to keep my goal in mind throughout. My sense is that my language skills depended on having this critical mass of foreign-language-only relationships. 
I'm not sure if the situation is the same in Bulgaria, and I'd be happy to hear your thoughts in response.