First a plausibility check:
My main heroine is an athletic, determined woman, 23 years old at the start of this story and approaching/perhaps reaching 28 years old by the end of it. She's a martial arts instructor the entire time; with college eating into her time between the ages of 18 and 22, and her needing to be a third-degree black belt to become an instructor, it seems plausible that she could start judo lessons at age 13, get her first black belt at 17, attain second degree rating at 18, third degree at 21, and fourth degree at 24. She would be competeing whenever it was feasible for her, would have been teaching since she was 22, and operating under USJF rules; her working goal right now is to one day open her own dojo, though she'd like to reach fifth degree rating first. Is my lack of experience with Japanese martial arts showing anywhere?
Secondly, a bunch of questions related to competitions: what are judo competitions like? What sort of buildings do they take place in? Are family members typically allowed along, and if so, can they interact with competitors when the competitors aren't actually competing? How far away would spectators be seated from the competition area? What are the differences between local, regional, and national competitions? What's the atmosphere like?
Thirdly, a bunch of questions related to instruction: my heroine has been studying at the same dojo this entire time, with the expectation that she could continue her studies there until at least she attained fifth degree rating. What degree black belt is the head instructor likely to have? How would her lessons have shifted as she climbed up ranks? How would her instructor duties have shifted?
Anecdotes are totally welcome.
Resources used: The Wikipedia article on Judo, Judopedia, and the USJF website.