Busy Philipps is realizing how undiagnosed ADHD impacted her performance in the classroom as a kid. Philipps, 45, who joined Jennie Garth on the Wednesday, May 14, episode of her I Choose Me podcast, said she felt like a bad student, but now realizes her experience was largely a result of her attention-deficit/hyperactivity disorder (more commonly known as ADHD). “You look back at the totality of your life and you're like, oh, maybe I wasn't an airhead. Maybe I wasn't terrible in school. Maybe my brain just worked differently,” Philipps said. “No one was really identifying it because as women, as girls, ADHD really presented differently than it presented in boys.” Girls with ADHD feel an "internalized" chaos, Philipps said, unlike the stereotype of a "hyperactive little boy running around." The organization Children and Adults with Attention-Deficit/Hyperactivity Disorder (CHADD) states that girls with ADHD present "inattentive" symptoms like "forgetfulness, trouble paying attention, and problems with organization," while boys' symptoms — including "blurting out or being unable to sit still in class" — present more physically, meaning teachers or parents notice them more, leading to a higher childhood diagnosis rate. Philipps said it wasn’t until her child Birdie was getting evaluated for potential learning differences that she realized she identified with many of the symptoms on the doctor’s checklist. She sought an appointment for herself and was diagnosed for ADHD at age 39. “My whole life has a different perspective. I was sort of always feeling like I couldn't get it together," said Philipps, who shares Birdie, 16, and Cricket, 11, with ex-husband Mark Silverstein. "There was something wrong with me. And now I feel so much more generous toward myself and my younger self.” Philipps said she's noticed a true change in her day-to-day life thanks to her ADHD medication, which has helped her focus. "I'm able to sort of prioritize tasks in a way that literally never in my life," she said. "When I'm taking my medication, never in my life have I been able to do this. And all of a sudden, I'm like, oh, I know exactly what I have to do. I'm gonna finish this.” Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from celebrity news to compelling human interest stories. Being open about her later-in-life diagnosis on her own podcast, Busy Philipps is Doing Her Best, has helped other women, who have reached out to share similar stories, Philipps said. “There are many, many women, older millennials, young Gen Z, who are really finding this late in life diagnosis to be incredibly helpful and finding ways of managing it better,” she shared.