I want to start this post with saying that you are not alone in feeling like you identify with your illness as being a part of your core personality. I was diagnosed as bipolar 1 when I was 14. (I'm now in my 40's) That's obviously been a huge portion of ( most of it really) my life. So I, too, tell people that I am bipolar, meaning it is me/I am it. I also have other MIs going on that I feel are part of me to differing degrees. So I want you to know that I'm coming from a place of understanding and empathy, not being critical which I am accused of quite often.

That being said, my experience has been that yes, the meds change me to a degree but they don't have the power to take away who I am. Do I always have a clear idea of who I am? No, and, honestly I don't think even normies always have a clear sense of who they are. Why else would there even be a need for forums of any kind on the Internet? We all want to belong and, to a degree, people are all chameleons IMO.
Do the meds sometimes numb me? Yes, but that is usually temporary and sometimes even necessary. My manias can get intense and they never stay in the euphoric state.(I wish I could figure out how to maintain that. God, I'd bottle that stuff up and sell it! I'd be so rich!!!) Anyway, it transforms into manic dysphoria, which is the current episode I've been in. The only sleep I get now(for the past 3 weeks) is by dosing myself with cold medicine.( Yes, that's OTC drug abuse, I'm aware of that, but I also visited my pdoc again yesterday & she's going to call in a script for Seroquel to help stabilize me. )

If I don't get stabilized, what usually happens is I crash hard....straight into debilitating depression. Now, Idk about your experiences, but for me this is not my idea of fun. It does mean I feel... Intensely(yes I intended to capitalize that).....but the SI that I get with my debilitating depression can/nearly has killed me. On several occasions.

So , in a nutshell, the meds, while they can sometimes numb me, are also literally my life savers. Frankly, sometimes I NEED to be numb. It, too, in a weird sense, saves me.
You can't live forever on sleep deprivation and all the other dysphoria that comes with mania. You can live in bed all your life from depression, but is it any real quality of life? I mean, yes, you can exist like that. But that's not really living, my friend, IMO.

Life is till gonna suck enough on its own, trust me. I don't need to help that along with making myself sicker than I am already. I have learned that stabilization isn't the same as losing yourself. You still have that and noone can take that away from you. Ever. But would it be so bad to be happier for a longer period of time even if it isn't as mind blowing as mania? Would it be so bad to not have SI, or to just not care at all? ABout anything? That being said, are you really always feeling "alive" with bipolar? Because I don't . I want desperately to feel better. Even if thatmeans I have to depend on pills to change my brain chemistry to do that.