Most ADHD experts will advise you to NOT disclose ADHD to your employer. While there are laws to protect those with disabilities in the workplace in the US, employers can simply find other excuses to terminate you if they want to. It starts the relationship with the employer watching for you to make mistakes and not be a good fit, giving you no time to prove your value and have them make judgements from that.
There may be some helpful strategies helpful to your current situation in this article:
ADDitude Community Moderator, Author & Mentor on Parenting ADHD, Mom to teen w/ ADHD, LDs, and autism