Is this a normal weight?, and how do I get the point across she isn't a pit?

I have 3-4 month old American Bulldog/Lab mix puppy around 3-4 month because she was born in June and she weighs around 20+. the vet didn't make any judgemeants when she weighed her but it was a busy day so I couldn't ask her and she was a bit busy and she ped her bill of health as did my eight week old collie puppy. Who is normal weight for a collie. I've had a lab before and she was only 10-15 pounds at this age. As it's the week end my vet is closed [my vet is also my breeding mentor] . I was just wondering if anyone who knew the American Bulldog breed knew if this was a normal weight, and about how big do you think she will get. Every one keeps telling me how beautiful my pit bull is and I get so stressed when I tell them she is a American Bulldog/Lab mix and they tell me no I'm wrong she is a pit bull. I saw both parents and know she isn't a pit. I had someone in the vets office get so flustered [they had a pit] they told me to stop denying my dogs breed just cause I was ashamed. My three questions. Is this weight normal? How big do you think she will get? and How do I kindly get my point across when people get so...demanding and stuff without them making a scene like at the vet.