As she gets a bit older she should get less likely to wander... should...
I think the best thing is to keep working on the recall in controlled settings and on a long line.
Other things -
Never call her to "come" when you can't enforce it (that's where the long line comes in).
Never call her to "come" when there's NO WAY you can compete with the distraction (i.e. horses, cows, squirrels, other dogs, etc.), she'll just learn that ignoring you means she can reward herself with the item that has her attention.
Never punish her for coming to you... EVER.
I use a more informal "come here" when there's a chance I might be ignored.... or if I know it's bad (i.e. a really fun dog to play with), I just quietly walk up to where I can grab her... no command, no punishment... just praise when she finally turns her attention away from the object and back to me.
We also have a very strong "right here" command - which is easy peasy to teach. Put a treat in your hand between two fingers, hold your palm out and say "right here" - when she touches her nose to your hand, she gets the treat. Move your hand in all positions, but always have a treat for when she touches it.
Then, when you're out and about... if "come" doesn't work, try "right here" and hold out your palm... for me, that works every time! (best to have a treat every time in the beginning, too)
The other one I have in the arsenal is a whistle and "this way"... when at the dog park or anywhere off leash, I'll change directions often where the distractions are minimal, and as I turn, I whistle and say "this way" in a high pitched voice (so it will carry)... then I just walk away from her. 99% of the time, as soon as Denna sees I'm heading off in a different direction, she comes RUNNING to keep up, and then pass me - at which point, I switch directions again, so it becomes a game.
She now will pop her head up to find me when she hears the whistle... to see where I'm heading now, that split second of focus will come in handy if you want to get a command in through distractions.
When you practice, be sure "come" doesn't mean the end of fun stuff... if you're at the ranch where she's having fun, and you ask her to come, then immediately put on a leash and drag her away from the fun... come will become a bad thing. We practice come as a "check-in"... at the dog park, during some down time (setting up for success), I'll call for a "come" - she comes, gets a treat and some love, then is released to "go play" some more. She also gets in the habit of 'checking in' with that - knowing it doesn't mean the fun stops, but that we can have fun together.
Good luck!
Patience and consistency are key, and keep it positive!
