https://pastebin.com/raw/gEwh393L
Note - the key is to approach these candidate companies more or less in parallel, and not serially. If you have multiple offers, you have a much better chance to make much more than what you are making today, compared to learning a new skill at this point.
Since you seem to have a lot of front end and app knowledge, personally I might suggest getting more familiar with back-end as a service technologies like Firebase, etc. You could then create apps/web-apps that scale without knowing loads of back-end architecture practices.
To get a good spot in a next company, practice explaining your accomplishments to date succinctly, meet people, apply to multiple companies and get multiple offers lined up.