Mine is 18 pounds but I guess it depends
My girl american bulldog 3 month is at 25pounds
I have 3 month old Male American Bulldog and he weighs 22.5 pounds. Females are smaller so it sounds like she is on track. Of course, that is assuming my dog is growing on track as well.
Mine is a female and was just weighed at 3 months and weighed 27.5 lbs
Mine was weighed at exactly 3 months of age and weighed 41 lbs but I am a breeder and keep my dogs on a strict diet of healthy natural food along with several small tricks I have learned over the years, also I breed bigger more bully types of A.B. So she is expected to be larger than your average.
Our three month male is 40 pounds we expect to put 10 pounds a month