Hyperventilation when speaking

Hey guys, just hoping someone could shed some light on this.

Basically I've had issues with my speech, tension for as long as I can remember now, unable to relax.

I've narrowed it down to the fact that when speaking, I tend to hyperventilate, which causes the feeling of not being able to catch my breath, or my heart beat starts to beat rapidly, the feeling you get when you feel you're gonna pass out, can't concentrate or focus and feel agitated.

Because of this, I get tense, tight around the throat, feel like I can't exhale for long so I feel out of breath when I speak.

I think it's because I read stuff about how to project your voice louder and because of it, I tend to overthink my breathing when speaking. So I will take a big breath when about to say a word. It's almost like I've breathed in, said a word then let someone speak then when I'm about to cut it or say my piece I take another big breath. I think I'm messing up the natural flow by thinking about it too much.

Can someone shed any light on the correct way of breathing when speaking to stay nice and relaxed and using good support to still be able to produce good volume correctly.

For the record I have been practising Diagrammatic breathing, I have no respiratory issues or vocal cord problems as I've recently had them all checked.

Thanks :)

Hyperventilation when speaking