What you are doing right and the others aren't is two fold.

First of all, you have a progressive series. A person can actually start from the beginning and work their way up to a conversational level. All the words are accounted for. You remind people of what is new and what has been covered already. You remind them in Chinese and use English sparingly.

This is the way that it should be done. After the initial stages, a language should be taught in the target language as much as possible.

The second thing – Lessons are introduced in Chinese.

I have a close Chinese friend who listened to some of the recordings on my IPod - she said go with CLO. She constantly remarks on my great accent which she says is always the biggest problem.
I travel a great deal and knowing Chinese, even a little, can only be helpful when 1/4 to 1/3 of the worlds' population speaks Mandarin Chinese. You are doing a great job - I seem to be going very slowly; however, my friend says I am not but rather she is impressed with where I am and again is most concerned about the correct accent.