Sorry so was I. Before I decided to leave a note I had something different on mind, then as I finished bascially just restating your acquisition, I forgot what I was going to say, the point. So I was gonna tell you try not to be too literal learning new terms. No matter what you call it "by the book", the point is to understand why you say like that, "what does it mean". Now that you've learnt the whachacallit, you should automatically have learnt something else as well --- in this case, how about "I was going to be doing that", "I would have been doing this if...", "she will have been doing..."
Get a grip. :)
Yes, you did have a good go correctly using that thing. Generally it's used to describe what you're gonna be doing in the future, and this action you take or activity you get involved will last for some while. Relatively long enough, considerably long. But sometimes the two forms you mentioned could be interchangeably replaced. The continuous tense places an emphasis on the fact that the whole progress is gonna take "<em>a while</em>" to accomplish.
Also it's "a usual..." not "an". The rest is perfect.