Bella is a 4 month old Lab mix. She is my first pup and I just want to check that I am doing ok by her! She understands sit, stay, down, up, go on and leave (she will obey these comands first time 90% od the time). She plays fetch well, knows the names of three toys and will find one of these toys if I ask her to (although she is still very slow with this one!). She plays tug of war well and understands when I tell her to be gentle. She fully house trained and sleeps all night. She is used to being left alone for up to 4 hours (with the occasional yelp and bark in protest!) She comes when I call her name first time 90% of the time. She is hopeless on the lead and is terrified of traffic. She travels really well in the car, doesn't get sick or anxious. She is very friendly towards people and other dogs and is very submissive. She jumps up all the time and is now trying to nip occasionally as she does this. She does understand when I say Off but she will still do it again and again. Sometimes he lunges at people and tries to nip them - is this just normal puppy play of should I be concerned? How are we doing?? I am surrouned by people telling me to do this and do that, and that Bella shouldn't be going that at her age etc....not great for the confidence!