Hello Victor
I can read passion here, one advice then, please do not wait to be fully integrated in a company in order to start with the tech aspect of the footwear. There are ways to improve your skills and knowledge before that.
1- read the forum such as running warehouse just to get an idea of what users are looking for or sometimes dislike.
2- visit the web site coroflot.com section footwear. Some designers had the brilliant idea to enclose the technical drawings of their shoes, extremely well detailed. In fact coroflot is one of the best footwear design resource to date as fore sole and upper .
3-type google patents and look for footwear brands, or whatever footwear related words and you will discover an incredible source of information that will boost for sure your control and creativity.
The goal consist to feed your passion, to improve your knowledge, to get you to the next level, the one that makes you attractive and why not a future colleague. Yo is right, sketch more, control more your silhouettes and concepts, pay attention to what makes a shoe performing. And please add light to your rendering as it is hard to distinguish where the shoe stops where the background starts…
Thats it
Good luck