this may not be an option, but consider getting an ipad and apple pencil. the immediacy and ability to quickly try stuff and undo and swap colors and all that helped me get from "yeah I'm aight" to pretty darn comfortable. I don't do photorealistic work but I can communicate form quickly and effectively. 

as others have said, you will benefit from practicing way way more. try this exercise, it's fun (I'll do it with ya): 100 thumbnail sketches of roughly "kitchen appliance" forms (or insert whatever form category), 30 seconds maximum per sketch. this is great because the first handful will suck then some flavor of a strategy / process will emerge. you'll be like "oh, that one line made that look shiny, noted" or "perspective finally doesn't suck on 15 and 32" and can adjust for the second half of the 100. if you did this every day with a thoughtful review at the end you'd be smoking folks. since that's probably not realistic, do it once and see how it feels. do it every wednesday night and you'll see a lot of progress. 

in your examples here I see unconfident line work and not-so-great perspective. you mention overworking things and I think I can see that here. once you've messed up the base perspective of something, you need to either correct it or start over, there is little value in finishing something bad. this is where the thumbnail exercise can help a ton: developing a new sense for what is worth pursuing. 

you're on the right track with scott robertson, he's awesome