Three of the 6 main girls have petite or athletic builds (only one is fully implemented though, one is halfway and the other is slated for the next update after the current one). Only one of the teachers have big breasts plus from the top of my head we got at least 6 others with smaller breasts as optional sex partners, and I think only the family of the protagonist really are all big tits? And of the future updates, after this one, the majority of incoming girls don't have big tits.
This was a complaint that was valid like, a year and a half ago, not now, imo.