Just a little confused

[fErReTs]

This is probably a really silly question but oh well . Well last night I was at a magic show with the WSPCR and I had my girl Suzy on display. Well to my knowledge Suzy is about a year and a bit old . Well there happened to be another Boa Constrictor there same age and from the same breeder but it was about half the size of Suzy. Suzy is about 3.5' - 4' long and and a okay thickness (I think she could bulk up a bit) .A breeder there told me she must be at least two or three because she has a female same size at three years old and told me to start feeding her every three weeks , so I don't know what to belive anymore . What is the normal size for a year old female Columbian Boa Constrictor .Thank you .