Play more nomod to get used to patterns you are missing playing mostly DT.
You can slowly up from 4* to 4'7* and from there to 5* building consistence, or jump directly to 5*-6* working on pass the maps and improve consistence after.
Also you can try to find high 5* and 6* maps what you already can pass or get really close/play decently, get used to similar maps and start moving from there to more similar map styles until get used to all of them.
Maybe you can play this decently since the patterns are not hard, just "fast":
https://osu.ppy.sh/b/732724Also the long maps usually are easier. For example a 5* 10 mins map usually it's 7 minutes 4'3* 3 minutes 5'3 or stuff like that where the diff start being really low and growing up at the end.
About high AR try to find maps with natural high AR nomod, are easier to start getting used to it, instead put mods at low * ratting. Focus a lot on the music and hitsounds.
Try to play the exactly AR you aim for. If reaction time it's the problem, play even a little higher AR than you're aiming for to get used to that reaction times faster.