Hey! Welcome to the world of Full Stack Engineering! You’re more than welcome here 
Though I don’t have freelance experience, I saw your post and thought I would share my 2 cents worth. I ask that anyone else with more experience add to, or correct me.
In regards to your feelings/frustrations, I wanted to share a saying with you: " Nothing good, comes easy." The way I see it, whenever I encounter a problem it’s a sign that i’m doing something right. No matter how small the problem is, whether it’s a semi-colon here, or 47 commits to get rid of a bug, i know i’m on the right path. Chances are there have been people before you who have had the same issue. Ease up on yourself. You’re doing fine
As for whether codecademy is enough for you to become a freelancer, I would say sure, but with a HUGE caveat. Hopefully I can explain this caveat with my personal experience. Again, my experience isn’t directly related to freelancing, but i ask that anyone who has more experience to add to my reply or correct me.
I use to be a sale’s engineer in Las Vegas. I worked with local structural engineering firms who designed some of the biggest casinos on the LV strip. I was familiar with their business. From what I do know about freelance, I feel like the business of my clients and the world of freelance are very similar.
Any client for a freelance web developer cares about three things: 1. Can this person do what I want? 2. How much of a risk is hiring this person? 3. Is the risk and the person’s fee reasonable? They don’t really care what certificates you have, or whether you have a Jedi level consciousness of javascript.
The firms in LV operated under these same assumptions. They did this, by bidding on projects in an intelligent way. They were asking themselves can they do the work in as little billable hours as possible, with as little risk to themselves and to the client. To sum this up quickly: If there was a structural engineer who could design the best casino in the world for $5k and do so in one hour, he would have A LOT of clients. The same principle can be applied to freelancers. If you’re a freelancer that can design Facebook level sites for only $1k and only spend 5 minutes doing it, I would imagine you will be very successful. Here is a prime example: Making $378K A Year As A Fiverr Freelancer - YouTube This young woman is killing it on fiverr (a freelance market place), because she is good at what she does.
The conclusion, there is a wide variety of work to do as a freelancer. The more experience and unique you are, the more likely you will find jobs and clients. Is there work in the freelance market for someone who just finished the full stack engineering skill path, maybe. Whether there is or not, it doesn’t change the fact that experience is key, and injecting yourself into as many problems you can will lead to you being more successful. Nothing good comes easy. Commitment isn’t easy, working on something and not knowing if it will pay off isn’t easy, but these are paths that people have taken to be successful. Stick on your path! You can do it!