I have used a retractable leash for Princess most of her life since we usually walk near home & not on any roads or even sidewalks along them. Well she's just becoming unruly & is not obeying 'wait' & 'up' etc. as she once did like going up & down the stairs (3 floors). There's also a problematic dog so if she's out 16 ft. it'd be hard to ''reel her in'' quickly.
So I bought a 6 ft. lead & hooked it to her puppia style harness. The harness falls at the very bottom of her throat yet she is practically gagging herself pulling so hard. She seriously looks like a sled dog & sometimes her feet even lift off the ground as she tries to lunge further forward. How can I teach her to use this without putting her safety at risk? I've went back to the other for now as I'm worried about CT & honestly very frustrated.

I'd like to just use the longer one for recreation to give her a little more freedom since we have an open yard, but the short one for car trips, etc. Will that confuse her?
Any suggestions?