DrForinor I wouldn’t generally be changing both grind & ratio at a single adjustment.
I’d also try and quantify with a score, so there is frame of reference, like how much better can the “sweet, very very little bittereness” shot be? If it’s 7/9 then there’s obvious room for improvement, but if it’s 8/9 might be as good as you get?
I’d try 1 notch finer at same ratio, if it flattens off, then try a shorter shot.
Out of interest, what is the origin?
Ignore the time if it tastes good/ballpark. If you used the finest useable grind then poured 70g of boiling water over the 14g grounds in a cup, they would never properly extract. That is how little influence time (alone) has on extraction.