I’ve been learning Russian for a few years, I’ve also started learning Serbian and Ukrainian a little bit.
I can speak Russian pretty decently, it’s my girlfriend’s first language so I’ve had a lot of regular practice with it, I don’t consider myself fluent at this point but I can hold conversations with native speakers without too much of an issue
With Ukrainian I can understand quite a bit but I haven’t had much practice speaking it with other people at all yet. I have the basic phrases memorized, things like привіт, будь ласка, доброго ранку, добрий вечір, дякую, як справи, etc. but I don’t think I could hold a conversation speaking only in Ukrainian. I’ve been studying it kind of off and on for a year or so, and I listen to some Ukrainian music fairly often
Serbian I’ve been struggling to learn, I’ve been working on it for about 5 months. I think learning Russian first made it weirdly harder since the sentences are structured fairly differently. When it’s written, I can understand quite a bit, but if someone walked up to me and just started speaking Serbian I’d be completely lost
I had the same problem when I started learning Russian and honestly the only thing that helped me improve was just speaking and writing in Russian more
the grammar is also really hard, but I found it best to just not overthink it and just get used to speaking and making mistakes but improving over time. It’s easier to focus on correcting grammar when you’re more comfortable just constructing sentences in that language in general and don’t have to think as hard for each word you want to say