Full stack development as a junior dev feels problematic. There's so much stuff to learn that the end results are mediocre and myopic.
Are you hung up on something in particular on the frontend or backend?
More of a general sense of "I can't ever actually become good at anything"
don't worry, with good time. i would say pick what you enjoy best (frontend, backend... devops even?) and focus on getting good at that.either way I'd suggest as first step to have a solid understanding of HTTP. reading the Wikipedia article should be sufficient.