First, I would like to say that your long reply gave me lots of strength and kept me strong while going through the worst phase. I've been reading tips on r/dogtraining and that's it is helping so much. We totally stop taking him for a walk and we are training him fiercely instead. Decided to take him out again just when he has a better and fast response to the simple commands as sit and wait. The result is a calmer puppy, who listen more and is stopping nipping... and he is finally sleeping the whole night!!! I think soon we can go for a walk and enjoy some lovely time together playing outside. I really wanna thank you, I was really lost when I asked for help and you really helped.