Yeah, you can move your feet! lol I use prime lenses, I tend to roam. So I think about my vantage point and if I need to adjust it before I take the picture. (But there's not a right or wrong it's more figuring out what works for what situation.)
I agree it looks awkward to crop people at the joints - I don't know the technical explanation but did you ever take drawing classes where you learned how to use a pencil to measure the proportions of your subject? it's been years so I don't know how to explain it but I think having taken enough art in school I learned proportion and use that in taking photos. I've done sports not formal portraits but I usually crop/end the photo just above or below the waist, mid-thigh, etc. - in one of yours the subject's fingertips are cut off. You don't want your subjects looking like mannequins that someone forgot to attach all the parts!
I think your background in art/design shows in the way you used the background, the skirt she's wearing with that graffiti, the one where she's imitating the graffiti'd drawing with its tongue out (that's a fun one). It looks like you need to think about your framing and perspective before you release the shutter - in that one the artwork figure's ear is cut off, when I shoot signage I include entire words/designs, or if I use part of a word I make sure it's straight and not cut off mid letter. (I did photos for marketing for a local team so took lots of photos of signage.)
I guess doing sports too I watch for lines like in the cement block wall, whether or not it's the perspective or making sure the camera's straight, I find that crooked lines especially near an edge of the frame can make the whole picture look crooked. I'd also think about the space, you probably don't want too much above the head and hands cropped off, as well as the backgrounds, that there aren't distractions in the shot.
To me it seems like you might benefit from a lot more practice with your camera and getting it set and focused and framing shots etc. before you get into doing portraits. Early on I used to make my eye move around the entire viewfinder, now I think it's automatic and I take in the entire scene, but I also try to watch to make sure nothing's cut off or sticking part way into the side or corner of the frame - I feel like either something should be part of the picture or I move around or reframe and get it out of my picture.
I do think you're right that you did pretty well, I just think it all takes a lot of practice, and it takes time to be able to keep all of the technical aspects as well as framing and composition in mind, til it becomes second nature.