Update 1: Ok, after looking at a bunch of my own videos and comparing to some pros, I think I've figured out a major issue that's contributing to this: I tend to not pulse (i.e. "go down") on rock steps. Instead, I bring myself "up", which also allows me to stick my leg back outside of my butt. If I commit to keeping my pulse and going down, then my leg has no choice but to be under my body. It also lends itself to a smoother "down" finish rather than a sharper "up" finish. This may not be all of it, but I think this will be a good place to start.
Original content below:
Right now one of the "big rocks" that I'm trying to change in my dancing is smoothing it out. What I observe is that I sometimes stall at the ends of lines/phrases or have a body shape that I don't like. This has a lot to do with rhythm; if I'm rushing I'll get to the end of the line too soon, which usually results in me doing some weird shape. If I'm stalling I'll cut the line short and force my parter to make up for it. What I want, instead, is a smoothness to my lines. Just barely getting to the end of the line as the next lead comes, or if it doesn't come, smoothly coming into that line end and being able to groove there.
This is proving hard. Part of it may be body awareness, too. I'll observe that my rock step doesn't look over my center but rather my right leg extends back farther and breaks the shape. Knowing how to do it correctly theoretically (keep your legs under your torso) isn't enough to be able to do it correctly.
I honestly don't know yet how to really fix and improve it, but here's my current plan despite that uncertainty:
One last concluding comment - I recently watched (for the 3rd time) a Laura Glaess YouTube video titled "What is my rhythm?" that I think lends itself to this issue. One specific thing this watch-through called out to me was her comment about the different feeling of "step steps" vs "triple steps". Step-steps are sharp, are like "wham wham!" (to quote her). Where as triples are smoother, more elongated. This may help to think about, especially really open moves like send-outs.