It took me awhile to get used to it. Them mouthing the other puppies is like us playing with our hands. And they can be very loud too! Lol. My Pomeranian is 2.5 years old. So he's the boss. And when he puts my lab, Axel, in his place. The first few times was terrifying! But you just have to remember it's all just noise it's how they communicate and let each other know "hey that hurt. Be more gentle".
It may take me a while, but I hope I'll get there. I know it's crucial for them that this sort of socialisation occurs so we will battle on,being brave (me, not Bailey)