I COMPLETELY agree with the long lead, it REALLY pays off, it's the best help to 'enforce' a command, I find it gives you control to redirect the focus, and they don't get into the play-running away from you game... .. that way you don't end up giving a command that is more like the hopeful question 'Please Come?' lol
I use 'stay close' as a command.. or a 'let's go' command or a certain whistle.. which means to just sort of 'come over here', so he knows I am changing directions on my walk... etc... because I only say 'Come' I REALLY mean it, and I never call him unless he's usually already running towards me or I KNOW he'll 'obey'...
I NEVER call him over or use the COME command to give him a 'time out' 'put him in crate', 'a brushing' or to put him on lead (i use 'leash on' as a command, lol)... My 'come' command is ALWAYS being treated very well (cheese is his thing) and/or generally I make a big fuss for listening...
With this simple method I found I had the most positive response in a dog ever, as Toffee comes running, even while chasing the 18 wheeler along the dog-park fence.. he turns on a dime when I call/whistle him back!! I seriously think that the long lead I used and the continued positive reenforcement is what made this difference and what worked better for me than anything else I had used on my previous dogs...
A sheltie who comes willingly and runs full tilt at you (bullet style) just because you called him is just the best reward EVER

So keep working on it as you are and the terrible teenage years will go by eventually, too
PS: I also agree with putting her in a crate, if not TOO long, or a smaller space, with no outside stimulation/windows etc to curb the barking when you are gone...