I'm a bit of a jack of all trades developer (front/back end web, desktop/native/mobile, a little embedded), and if I were to point out the main issue here, it _sounds_ like the projects/jobs you've worked haven't either given you opportunities to be mentored in newer tech/work-flows, or haven't given you opportunities to learn on your own. These issues could be your own fault, too, I don't know. For reference, I've been a hobbyist developer since 2001, professional since 2010.
The thing about working in tech, is no matter what you work on, technology is always advancing. There will always be newer, better, and more accepted ways than what you're doing now.
For instance, in 2007, it was perfectly reasonable to use bootstrap and jquery, and boom, you have your responsive layouts, animations, etc. You can still do that today, but I think that would be considered legacy by most developers. Now you need to have a decent grasp of raw css (v3, which has a lot more layout-related directives), and vanilla javascript.
Having knowledge on core fundamentals has a lot more value than knowledge in libraries, and that's been the case well before 2007. If you invested a lot of time in bootstrap+jquery (or whatever tech you/your company chose in 2007), those skills aren't completely wasted, but the investment in how javascript, as a language, works, or modern layouts in css are much higher value.
If you've lost your confidence/will to apply to newer jobs, that's a deeper issue than just switching from front-end to back-end. Working in software is literally having to learn and re-learn the same things over and over as technology improves, or the ways languages do tasks change. The only thing back-end may give you is slightly more stability, but even that isn't guaranteed.
So before you go all-in on switching from a front-end only to back-end only, maybe there are some questions we, as a community, can help you resolve.
- Do you have anyone mentoring/guiding you through all the changes that have happened in web tech since 2007?
- Does your job give you any opportunities to grow?
- What is the single biggest pain-point daily for you, and is that something we can help you solve?
- Are you disinterested in front-end technology, or just overwhelmed?
- What is so appealing about back-end over front-end?
I hope I haven't come across as uncaring, I truly hope we can sort out the issue you're having <3