The diagnoses is most of the time not that easy. I was diagnosed really early with 16 after a suicide attempt with 13. I was diagnosed with MDD and ADHD at the time and the SSRI and amphetamines stimmed me right into my first manic episode with psychosis. If you are BP 1 and have psychosis while in a manic episode the diagnosis comes pretty fast. If you are BP 2 the diagnosis can be a lot harder because most of the time when people come out of a depressive episode they just feel "normal" before spiraling and getting erratic when in hypomania.