From what you’ve said, I would be inclined to suggest that you are consistently dipping. When you said that you were aiming high and hitting low and left before upgrading the trigger, could the “low left” been about 7 o’clock? For a right handed shooter, this indicates trigger jerk as well as dipping. Have someone else shoot your pistol to see where it impacts. If it impacts point of aim, then its you. The first thing I recommend is dry firing. Anywhere from 15-30 minutes a day to start, and 10-15 after that to maintain. Just make sure the pistol is unloaded and the ammo is far away from the gun (another room) when you practice. I’ve seen shooters over the years switching to guns with lighter or better triggers, or smaller, lighter recoiling calibers and find themselves shooting more accurately - for a time. Then the old habits resurface for lack of focused training and they’re back to having issues.