Designer said:
I am simply stating the issues I encounter, as I encounter them, in the hopes that someone here will relate ..
I relate. Issues of my own.
It's good to hear some of the back story behind a set of photos; knowing how/what/why can give us insight. You're short, and so you got up onto an elevated shooting platform, and found it was precarious, and also lead to the shooting down on subjects POV, which shows up the most in #4 of the older boy, and I'd say that there was a valuable lesson learned there. But as you said, you got light subjects in front of a darker backdrop, so you got subject
Pop! and separation. The lighting is smooth and not awful, nor squinty,etc.,etc..
So...I wondered to myself, what could be improved,quickly and withiout much effort, with these? What would
I do with these shots? I pulled them into LR, and frankly, there was not a lot wrong with your initial JPEGs. ANY photo can retouched for an hour, or two hours, but that's not the point.

cropped a bit, minor adjustments, I am not super fond of this cross-body eye glance,and its sort of the odd shot out from this set, lighter, and different than the others.

Minor WB adjust, Vignette #1 from Lightroom. A strong shot! Pleasing rendering! She looks great!

Cropped this more tightly. White T-shirt might have UV brighteners in the fabric itself, which is common, and makes it photograph a bit blue-tinted but that makes the shirt look super-white to human eyes in the real world. Whites of the eyes look good, but the shirt is in evening light, so a little bit of blue tint is somewhat expected by many people. Maybe could use a little bit of WB warming.

Cropped into this quite a bit, and gave it a slight rotate CW.
One thought, I like to look at, crop, and judge shots like this as small images on-screen, so I get a sense of the overall gestalt of the image. If I like the shot as a thumbnail-sized picture, I will most usually like it as a large image. I hope you don't mind me showing these minor reworks, Becca. I think you can see they are for the most part much better than they are bad!