Am I working towards the wrong thing ?

I'm not sure you are doing anything "wrong". This really is 80% mental, so how you think about it might be all it takes, and trying a few different approaches to find what works.

Here's one thing you could try: Don't try to relax. Don't try to tense up. Be an observer. (I know you say if you don't tense up the orgasm feels like its coming but never comes - just observe that and pay attention to the tiny sensations, dull aches, and notice how that feels, and where it's located, notice if it changes locations)
So as you start to feel things, you might notice how relaxed you are. Try to stay that relaxed.
As you notice a part of your body start to contract or grip or tense up a little bit, just notice that. Try to just let your body stay where it is (don't intentionally relax or contract). Just keep the state you notice you are in. That actually might take some effort cause you'll want to tense up or relax for whatever reason (comfort, or it just feels good).

It's sort of like the "do nothing" method thats mentioned here in places like the wiki. But I prefer to think of it as the "try not to have an orgasm method". It's almost like trying to just not do anything makes you involuntarily start to do something. And if you do start to involuntarily tense up, or relax, or do something: what do you do? That's right, do nothing and just observe 🙂

My mindset when things really get going is to "surrender" and let my body take me on a ride...without me steering the car so to speak.