Overall, I think you are indeed following the core concepts and instructions of this lesson fairly well - there are a couple issues that I want to address, but as far as your concerns that you're doing something inherently wrong, I think you're probably fine on that front.

Starting with your form intersections, these demonstrate a really clear grasp of how forms interact with one another in 3D space. You're handling especially complicated intersections with a lot of confidence (like those between spheres and cylinders), so I'm pleased with your results there.

Moving onto the actual meat of the lesson, the first issue I want to point out is actually very minor, but still something to be aware of. In the instructions where I mention that you can use a variety of different tools to help, I point out that regardless of what kind of pen you choose to use, you should use the same one throughout the drawing. This also includes matters of colour. The reason is simple - I don't want students to treat the subdivisions and the drawing itself as being separate things that could ostensibly be removed from one another. More specifically, I don't want students to go on to redraw the entirety of their drawing on a grid - instead, I want their drawing to incorporate the lines from the grid, and to use line weight to help create the sense of separation, of which lines are coming out and which lines are being left in the back. Part of this is because I want to avoid issues where students try to trace back over their grids - tracing itself is something that usually results in students focusing too much on how their lines run across the flat page, rather than how they represent a three dimensional edge in space.

Moving on, I think you definitely show improvement over the set. With your first drawing - the game controller - you rely on the subdivision a lot less than you really should, and end up guessing the positioning of things like buttons and joysticks relative to one another, instead of firmly establishing those locations in space based on more specific relationships. This is something you dig into much deeper in later drawings, pushing your subdivisions a lot further to find more specific positionings for things, like with the speaker box, the xbox, and the light bulb.

Also, in the game controller, you have the sides stick right out of the enclosing box, and generally have a much looser relationship between the constructional elements, the straight, measured, solid scaffolding, and the more organic, curving elements of the construction. Remember that as discussed here in the lesson, curves are a last-step thing. We want to make sure everything is built out to be really specific in terms of how it sits in space, with straight/flat surfaces and edges, then rounding them out as needed. You can see an example of a controller taken much further in terms of building out the scaffolding here. Even this one could have been taken further, but it is definitely still very specific and quite precise.

When it comes to the fact that the controller stuck out of its enclosing box, we run into a similar issue in this perfume bottle, although this one was handled somewhat better because of how it still clung to the side of the form. That said, it would have been much better for you to have extended the box out on either side (using this mirroring technique to extend either side out by the same amount), then built out the protrusions for each side (using subdivision to position them accurately), and then smoothed it all out in the end. Your approach here definitely skipped some steps, and as a result the left side appears to stick out a lot more than the right side.

The last thing I want to mention is that this drawing was definitely planned out more thoroughly than the others, but you missed an opportunity to apply the orthographic drawings (the side/bottom/front) more effectively. What you could have done was study the specific proportions of each side - find whether a certain feature should be positioned halfway down one side, a quarter, an eighth, etc. and get specific subdivisions in place to properly place every little feature. Additionally, the drawing itself ended up being really small, which definitely restricted your ability to work through those spatial problems.

All things considered, I feel the issues are more that you could have pushed a number of these drawings further in how far you took the more tedious steps. The core understanding of how things were applied was fine - it's just that you perhaps didn't exhibit the patience required to really push each drawing to its fullest extent.

Keep this in mind as you continue moving forwards. I am certainly satisfied enough to mark this lesson as complete however, so you'll need to demonstrate these qualities in later lessons.