Yep, there are no junior sizes in cycling clothes.
Not too many basics in juniors, either. I have eyed a few tees, but I rarely shop in stores, mostly on line. I wore junior sizes until I was close to 40, but thankfully petite sizes became more common. I am not as small as Eden, but my mom wore a size 4 shoe; that was OK when my family owned a shoe factory and 4 was the sample size. By the time she was looking for shoes for my wedding that was over, and she was desperately shopping at Nordstroms, where she did find something. She did buy kid's sandals and casual shoes, though. While I wear a size 6 in casual shoes, I wear a 5.5 in dress shoes, with a closed heel and it's tough at times.
2015 Trek Silque SSL
Specialized Oura
2011 Guru Praemio
Specialized Oura
2017 Specialized Ariel Sport