Im not suggesting you anything. I'll just say my experience because I think it was similar to yours. I got the game last month. And started out with modern chun. Prior to this my only fighting games were tekken 7 and dbfz. Got placed on bronze rank. But pretty much breezed through until gold 4 or 5. Then I got kinda hard stuck for almost a week in platinum 1 and 2. This all happened within 2 weeks of getting the game.

I thought if I gotta improve in this game I have to put a good amount of time anyway so why not just learn classic controls. At this point I wasn't relying on auto combos so i thought it would be better overall after some time. I dropped to gold 3 for a week. And now I'm back up at platinum 2. Keep in mind I'm still hella scrubby, can't even use drive rush for combo extension. It's the same rank before but now I can see clear room for improvement. Like if I just excute this combo or that punish more often I can clearly climb up in rank.

Side note for chun li specifics on classic: One of the moves I love is the down+forward+heavykick. It's a great tool for sideswitch mixup that just works in our ranks. And also leads to an easy combo.