How to improve in in OSU! (6-5 digit)

I’ve been rank 250k for a while now and haven’t improved since I reached that number. I’d like to become a 5-digit player any time soon but I have a problem.
I usually play 5* maps, but the hardest map I ever passed was 6.52*. I started playing 4* maps to get some FC’s there, but can’t quite get them. I end up having pretty much same ACC on both 4* and 6* maps (around 90%, I usually play jump maps). When I try to play those maps on Relax, I end up having 100%.
Is there any way to improve my timing since I feel like that’s the biggest problem here?
My account if needed: https://osu.ppy.sh/users/18951466