On the subject of UX, I wonder: are you already doing user testing sessions? If you are, nevermind my ramblings...
TL;DR: Get 3 users a month to have a Zoom/Teams/whatever screensharing session where you watch them use the site while you take notes.
I'm (somewhat) in charge of the process of including user testing sessions in the dev process of the startup I work in. I'm a coder with no specific UX training and have just been self-learning this. My experience has been that even really crude and non-rigorously designed impromptu sessions are useful because without observing actual users actually using the site you can make surprisingly terrible mistakes in design that you don't notice because you see the site from the viewpoints of a developer who knows exactly how everything works. It's pretty much impossible to accurately simulate the experience of a clueless user in your own mind, you have to see it for yourself to understand what things in the UI are actual problems.
Doing user testing sessions can be started immediately without needing to hire a specialist. You don't need a UI/UX specialist to do them though someone with such experience can provide additional effectiveness to your UI development. MangaDex already has a very large userbase and I think it'll be pretty effortless to, once a month, recruit 3 people to do a 15-60min session without needing to pay them. A session consists of watching somebody use the website while they narrate out loud their thoughts and what they're trying to do. Crude and simple sessions can be really useful when you've never done any sessions at all. Being increasingly rigorous in the testing setup becomes necessary the more polished your UI becomes because the remaining problems become increasingly subtle and harder to notice.
http://www.sensible.com/rsme.html
I read the books Don't Make Me Think and Rocket Surgery Made Easy when I was first figuring what user testing is, they seem like pretty good starting points.