Still a long way to go, probably gonna re-do the upper leg parts, lower arm parts and add some upper arm armor. I'm also thinking of getting some pouches you see on today's military equipment. The armor in general still needs a lot of finishing off.
i'd have a three or four piece abdominal guard that goes low... overlapping from the bottom up with your codpiece overlapping your waistguard, your waistguard overlapping your lower ab plate, up until your upper abdominal overlaps your chestpiece... or just one solid stomach plate that overlaps the chestpiece like medieval armor
I would suggest dropping the leggings down to the knees, and adding some underlayers to the upper leg to fill the space. those pieces look good, and seem like they would make good knees. you also might want to consider adding a "reinforced soft armor" sleeve bridgeing the shoulder and wrist.