Hi, there! Thanks for this excellent translation. There are just a few things you should consider - here are my suggestions.

Já aprendi a lição de uma só vez > I learned the lesson all at once
Without discovering the reasons > Without ever discovering the reasons
I struggled against the world to have you > I don't think 'struggle' is a nice verb to be used in the context of a song and its translations. It's correct, but I would personally translate that line as 'I fought the world to have you'

'Porquê é que tem de ser' is actually an indirect question - it doesn't use a question mark because the rest of the question lies in the next verse. Those two lines then have to be translated as Why does it have to be / A farewell which I can't understand. However, the usage of that word is wrong - this tricky word has four different versions which convey different ideas and people must understand them from the context they're in. I'll correct the lyrics now.

And you got that 'my being' thing right. We generally use that to refer to our existence, but you can technically (and correctly) refer to your soul.

Congrats :)