[troubletb]

I have a puppy that is 2.5 lbs and one that is 7.5 lbs and they are rough and stuff with each other, the only problem I have is the bigger one can get on the furniture and then the little one sits there and whins until someone picks him up on the furniture and then you need to put him down again when the others jump off...LOL but he takes the roughness just like the best of them. As far as her being big or small, you have no way of knowing until she is grown. The only thing that is wrong with this sistuation is her age. If she is adjusting and you love her, just keep her and love her some more.
PS: What does your vet say about her??