Sentence Construction

[tiong603]

Is the construction of this sentence correct? If not, why?

I argued with them until I was blue in the face, thinking that I was only wasting my time.

[Anglika]

Welcome to the forums!

It is fine.

[Casiopea]

You could change thinking to knowing (full well),

A. I argued with them until I was blue in the face, knowing full well that I was only wasting my time.

B. Knowing full well that I was only wasting my time, I still argued with them until I was blue in the face.

[tiong603]

Your co-operation is most appreciated! Thanks.

[Soup]

You're welcome.