//My argument with most people claiming to love liberty is the definition of "harm". They usually believe that THEY can determine what harm is for anyone else and that it is always objective. i disagree.//

I don't believe that I can determine what harm is for anyone else, I can only determine what "harm" means to me.
I.m.h.o. that is the purpose of the NAP to get you thinking for yourself and determining words for yourself. It's not a dogma or law it's a principle which may be observed and reacted upon in "reality" however flawed and subjective that may be.

What is left if I can't determine what is right.
In that others determine for me that I can't determine the word or action 'harm' for myself.
That if I get attacked, raped, stolen from or someone is trying to murder me (what I see as harm) I must question myself if I'm right about defending myself because, me calling those actions harm, is (to others) subjective and therefore may be incorrect?

Are words of love not also subjective, what may sound like words of love may as well be words of manipulation, how can someone tell the difference if not by judging the action and naming that action a certain way?

One last question about the title; Is the NAP valid?

What is valid, and does it even matter what others think is valid?
I as an individual think that all I have to do is look at the deeds of myself and someone else, what words are attached to the deeds do not matter.
I have to make up my own mind. In the most literal sense of that sentence.
And a sentence it is.