Hi Arahel85, I was in a similar boat. I wasn't asked to completely redo lesson 3, but I also struggled to continue with the course after Uncomfortable said "parts of your submission were so bad I almost gave up on the critique and just made you redo everything." Of course that's not what he wrote, but that's how I read it. Even after he clarified I had to take a break from drawabox before I was able to properly reframe things.

What I eventually realised is that this is not about the quality of the drawings. In fact it's the opposite because a lot of the ways in which we deviate from the instructions actually result in better drawings, at least in the short term. You can see that mentioned this in his feedback to you:

Yes, it may lessen your accuracy and result in your line weight separating from the initial mark, but there are two things to keep in mind for this:

...everything we do in this course is an exercise - so if you're going to make mistakes, in order to learn from those mistakes, there's no better place to do it than in your homework.

You do have concrete steps to take. You don't need to come back with gorgeous masterpieces or fundamentally re-evaluate your understanding of the material. Uncomfortable just wants to see that you're doing all you can to follow the instructions. If you apply everything he said in the critique he gave you I'm sure you'll pass even if it looks bad. You can definitely try to apply lineweight in a single stroke, you can certainly include a minor axis when building a plant pot and it doesn't take any extra skill to resist drawing additional lines when constructing branches.

I think the reason Uncomfortable is so strict with the lesson 3 critiques is that it's an opportunity to drive home that these are exercises first and foremost and making nice pictures takes a distant second to closely following the instructions.