Hello, We're struggling with our Pup Molly, she's 19 weeks old currently and displays behaviour that I honestly can't tell if is aggression or play. I was hoping someone may have had similar experience to me and advise on whether or not it sounds like my puppy is showing true aggression or is just playing aggressively. The problem is specifically when she wants to play and it's time for the play to end, for example - she bites the cuff of a trouser as we're walking past. So we exit the room and shut the baby gate, as we approach the baby gate she may bark even more, growl etc telling us it's not time for play to end. Or sometimes Molly is the one who gets placed out of the room as there can be up to 4 of us in the room at one time, including 2 younger children. In this case she might start backing away as we go to pick her up, barking/growling at us - I have noticed her tails wagging along as she's doing this. I see it as a sign she's not wanting us to remove her, however shes being removed for trying to bite/mouth one of us. It came to a bit of a head yesterday when she managed to get upstairs when someone wasn't quick enough to shut a door she's normally not allowed through. She got upstairs and chased one of our cats and was barking away at her, I followed her up to bring her down. She displayed the usual behaviour, backing away a little barking and when I went to pick her up she nipped towards my hands. She had gotten very excited at the cat and she does tend to mouth a little more when excited. It's confusing as through all of these her tails wagging, she doesn't go stiff or snarl. She just growls, barks and has only once nipped as mentioned above. When I say she's backing away, she's jumping around with a lot of energy moving backwards - rather than a slow cower away. Again this makes me think, she might perceive it's all a game. Honestly, I'm just worried we're doing something wrong and whatever it is she's hating enough to be aggressive.