Inability to Speak Native Tongue Fluently?

Unfortunately, as the schools I've attended in America don't have a secondary language as a requirement, my native language is the only language I know fluently. I suppose in regards to your initial question, this is a good thing because I don't mix it up with anything. However, every time I get acquainted with a newer language, I often want to jump straight to the advanced vocabulary, which makes the language somewhat difficult to learn.

I can't imagine how ackward it would feel to be speaking in one language and switch to another language in mid-sentence. However, just recently I was talking to a client at my workplace and she was describing to me how she recently went to the doctor and resorted to speaking in her native tongue just because that's her most comfortable language.

Jam it back in, in the dark.