I'm 21 in like a month, and didn't fully accept that I'm also attracted to girls until like a year ago; it messed me up more then when I realized I wanted the D back when I was 12.
I started to self identify as bi at 15 so my questioning stage was more at ages 11-14. I started identifying as bi as soon as I learned about it, so if I had known about the existence of bisexuality earlier I probably wouldn't have questioned myself for as long
I came out when I was 20 and then slowly became more and more comfortable with being myself. I'm 22 now and in a relationship and honestly wouldn't change it.
Just turned 21 too. Don't really care at this point what people think, I'll tell them if they ask but I'm not wearing an "I'm gay" sign on my shirt. I've learned to accept myself because my attraction to guys won't go away and I'm happier this way.
I'm 21 and pretty much good with it. I think for the longest time I felt like I had to be one or the other, but now I've fully realized myself and its all good.