It’s tougher to get an adult diagnosis because ADHD was thought to be a childhood condition that was outgrown in adulthood for a very long time. It really stuck and a lot of clinicians still believe that unfortunately.
And ADHD can look very different in women and girls:
Your best bet is to find a new clinician, maybe even seek a new evaluation to make the diagnosis official so you can be taken more seriously.
ADDitude Community Moderator, Parenting ADHD Coach, Podcaster & Author, Mom to teen w/ ADHD, LDs, and autism