Hello,
Your dog's behaviour is completely typical of a cross between these two breeds—a bundle of energy that needs constant stimulation. To help manage all that energy, here are a few tips to address your concerns.
Firstly, teaching her to be calmer outdoors starts before you even leave the house. It is essential to maintain a sense of calm at home before heading out. If your dog starts whining or jumping around as soon as you pick up the lead, put it back down and go back to sitting down. Try again once she has settled, and don't hesitate to reward her with treats to encourage her to stay calm. Then, during the walk, you can introduce 'quiet time'. To do this, simply sit on a bench and do nothing; this limits excitement and encourages calmness (ignore her attempts to get your attention—look at your phone or read). At first, she will get impatient. As soon as she finally sighs and sits or lies down, praise her with a calm, slow stroke. Repeat this for 10 minutes during every walk.
Regarding weaning her off sticks, it is true that this isn't easy as she seems very playful and the stick acts like a bit of a 'drug' for her. To break the association of 'walk = stick', it is necessary that if she finds a stick and brings it to you, you ignore her; do not pick it up and do not throw it. Over time, she may get bored and give up on this stick obsession. If that doesn't work, you could replace the stick with another object and teach her to carry it on the walk, without ever throwing it. This will soothe her and satisfy that Border Collie/Beauceron need to have a job to do.
Finally, the fact that she hardly plays with other dogs anymore is perfectly normal—it’s a sign of maturity! Given her breeds, she is very focused on her human (you) and her environment. For her, interacting with you or exploring her surroundings is much more interesting than chasing after another dog. The fact that she greets them politely and then carries on with her own thing shows that she is very well-socialised. She isn't aggressive; she’s just selective.
I hope this helps to answer your questions. Wishing you many wonderful adventures with your dog!
Best wishes,
Laure.
Translated from French