Hello Cathy, thank you so much for sharing your fabulous pastel drawing.
Absolutely yes to your question as to whether you’re on the right track on this, and here are my thoughts.
I checked the reference photo you mention and I believe that your drawing is much better than the photo in its richness in colour and value nuances. I prefer your drawing to the one that was completed by Matt because your version appears to slightly emphasize the wildness and naturality of the scene compared to Matt’s version, which strikes me as being a well-kept garden. I guess Matt drew this scene this way because he wanted to simplify the drawing process as he drew this piece as a teaching material maybe?
Anyways, my only suggestion for improvement for this particular piece is to add some more pastels to fill the unpainted areas that stand out as white spots here and there. As a reference, would you please check the following link where I showed one of my own pastel works:
For the recent 4-5 years I’ve been drawing only ballpoint pen works, but before that I was doing a lot of pastel works.
You can probably see that there are not white spots left either in the brown columnar joints areas nor in the green leaves areas at the bottom. This is what I mean by “fill the unpainted areas”.
In my very first pastel works which I drew in a local pastel class, I did leave the white unpainted areas too as you can see below:
Fortunately, though, I was able to examine the actual pastel drawings done by my teacher then in the classroom and I found out how neatly the surface was covered with pastels.
So I started practices to cover a small drawing paper with pastels completely. These are something I drew as part of my practices:
I wish I could show you the actual pieces, not the digital version, because then you can see how “thick” the pastels are put on the papers. I frantically repeated layering pastels over and over and over so that the work would not appear to be unfinished. I also learned that by layering pastels this way, you can fully show the real depth of the colour of the pigments.
After I practiced layering a single colour properly I moved on to the practices of gradation, colours mixing, and different colours layering without mixing. Here are some of the results of my practices:
So I think it is really good to try the course materials first to quickly grab what it is like to draw with pastels and see whether you would like to be good at it or not in the first place. But once you decide that pastels are the art medium of your choice, I think it is better to follow the Descartes’ policy: “divide each difficulty into as many parts as is feasible and necessary to resolve it”; i.e. identify the basic skills used to complete the pastel artwork which includes a lot of information, so much so that it makes you confused about where to start, how to finish etc… Learn the skills, then refine your learned skills to your best by drawing some simple subjects. Then you’re ready to draw some challenging subjects:
Hope this is of some help for your future projects.
Thank you again for sharing your fantastic pastel work! 
