I a software developer going into UX/UI work and learning on the job. Help please

I am new to UX as professional thing. I have been a developer for several years, and a frontend developer for the last 4 years, I am not the best at it, but not the worst either. With time I got more and more interested in the UI/UX aspect of frontend, and finaly I have a really nice job, where I am working as a whole in one! UX/UI/Frontend, I know this are three different roles, that can be split amoung 3 different people, but that isn't happenning so soon, I work at a startup, and I will have ownership of these alone for a while.

The problem is, although I am able to deliver on the development side, I lack organization and training in UI and UX fields (but I really want to get some! Since I really love what they involve). Until I am able to get some proper training, what do you recommend I try to develop those skills? From how to do wireframing to how to make a UI look nice? I know the question is very vague, but right now I am in a situation where I am drawing some wireframes, trying to make myself as clear as possible to my managers, before going into implementation, but I feel that I can never be as clear as I wish, and that I will block as soon as I need to make it look nice and be user friendly.

So here's what I have been doing, wireframes to spark conversations about how everything should work, moodboards to get inspiration about how everything should look. I have skipped user personas because I don't feel confident enough to do them and make them make sense with everyone else. I haven't done any user research because, we know who our users are but can't really speak a lot to them. Most important of all time is short (as always!), how can I learn in parallel to my work about UI/UX techniques a methodologies? Any suggestions are welcome, from daily short challenges, to which tools I should look into, to what articles/books are a must read (already read. 'Don't make me think' :))

Thanks for all the help in advanced I am really feeling a bit lost here :)