Hi @Former-Member. It's lovely to make your acquaintance. 
Firstly, I would very much like to echo the thoughts of the other fine peeps on this thread. The diagnosis is just a label. It definitely does not change who you are and have always been.
Having said that, having a diagnosis label is an incredibly powerful and useful thing, IMHO. To me, knowledge is power. The more that I know about my condition, the better I am able to survive, and even thrive.
My journey through my own mental health issues has been made easier by having that label. It gives me something to focus on, to research. I can learn as much as possible from outside sources, and then compare it with what is actually going on inside my own thoughts and moods. Over time, I have been able to build up a fair bit of self knowledge, which helps me to understand what my triggers are, and how I can manage to live my life in a much more helpful way for myself and the loved ones around me.
Bipolar has a bit of a bad reputation. You hear about another movie star gone off the rails, and bipolar gets a major billing all too often...
I posted about my diagnosis trail in another thread here. (I hope the link works - first time I've tried it here on this forum)...
It's been a very interesting journey, and I have been lucky to share it with fellow mental health consumers. Our shared experiences and knowledge has helped make the journey very much easier.
Acceptance. That is perhaps one of the most important things in life, leading to an improved condition. I have learned much by accepting instead of fighting things I cannot change. It allows me to focus my energies on things that I can change, that I do have control over.
I wish you all of the very best in your journey. There is much wisdom and knowledge out there in the greater community.
Hugs and happy vibes beaming to you. 