Why the hell does this keep happening? I still hear horror stories of how people struggle for half of their lives and nobody stops to think "this isn't normal, we should see a doctor" and it just infuriates me.
Please, if it is negatively effecting your life or you get into arguments about it and it's effecting your social or home life, see a doctor.
Almost the same age as you and I'm fairly confident I'm undiagnosed and have been since about 3rd grade as well.
My mom had such a diagnosis suggested to her multiple times but felt the stigma of a diagnosis and a medication to treat it was worse than just doing nothing. In her mind, I'd get diagnosed, given a label that would prevent me from ever getting a job or having a normal life, and drugs I'd take for the rest of my life that would make me act like I'd received a lobotomy.