On New Year's Day she recorded her biggest victory yet when landing a Listed bumper on Henrietta Knight's Precious Metal at Cheltenham.
Yet at the same time as leaving her mark on a male-dominated profession, she was carrying a secret that only those closest to her knew about.
Lilly has been living with ADHD, attention deficit hyperactivity disorder, since she was diagnosed aged three.
And after achieving her lifelong goal of becoming a professional jockey, she has found the confidence to go public about her challenges in a revealing film, 'A Racing Mind', which documents a year of her life. In one clip, Pinchin says: "If I didn't have horses, I'd hate to think where I'd be right now. Every day I wake up in the morning, my brain is a mess."
And, on the eve of the Cheltenham Festival, she says: "Racing is a small and close community. I didn't want to publicise my condition because I was scared.
"My biggest ambition was to ride out my claim and I didn't want trainers, owners, fellow jockeys to judge me for having ADHD because a lot of people refer to a person with ADHD as someone who is crazy.
"I would be if I wasn't on my medication, but, otherwise, nobody would know that I have it because I manage it very well."
Lilly's parents Nadine and Darren, a former rally driver, have provided the bedrock for their sometimes tearaway daughter who left school at 15 with her heart set on her career path. She got her first job with Fergal O'Brien, then became conditional rider for Graeme McPherson, ...