Am I too afraid of lung barotrauma? Remedies/Techniques?

[Miyaru]

...
I am so scared of rupturing my lungs that I think I exhale way too much. It distracts quite a chunk of my mind
Why am I so scared?
...

You have seen many reasons why it's unlikely that you'll injure your lungs.
I want to take a different approach and explain how you can injure your lungs.
Disclaimer: if you really want to try this in real life, forget the Boyle part and go for a Darwin award

Barotrauma requires pressure differences and Boyle's law is all about that. Boyle stands for:
Breathe Or Your Lungs Explode

As mentioned before, it doesn't matter how deep you are, what matters is the change in pressure. That change is the largest in the final meters towards the surface. So for the lung-damage-experiment, a swimming pool is all you need.

How much can your lungs handle? If you inhale completely, and then some more (lung packing / buccal pumping), you've inflated your lungs to the maximum. No way you'll get more than this into your lungs. The easy way to achieve the same is to go 86cm below the surface (body horizontal) and breathe in completely from your regulator. If you hold your breath and surface, your lungs won't explode. Yet.
So for some proper lung damage, you'll have to go deeper. 2 meters deep in the swimming pool will get you closer, 4 meters will increase the chance of damage. But.....you'll have to keep your chin on your chest, looking down.
So....recipe for disaster = hold your breath + last meters to the surface + chin on your chest.

Remember that for resuscitation, you have to do a chin-lift and/or tilt the victim's head all the way back, in order to open the airway.
When you learned how to ascend, you were taught to keep your hand on the deflator button, reach up with your other hand and look towards where you are going: up. This also opens the airway.
When you did the CESA exercise with your instructor, he was slightly above you during the ascent. You had to look up towards your instructor. One result is that you opened your airway.

Holding your breath with your head tilted backwards while ascending, is next to impossible. So as long as you look up to the surface, as you learned during the Open Water course, your lungs will stay as healthy as they were before the dive.

 

[Celt]

...and that is why I would personally choose to do a normal ascent, a CESA, or a buoyant ascent rather then try buddy breathing in a real OOA emergency. The only exception on an NDL dive would be if the other diver was someone with whom I had practiced buddy breathing, and since I don't practice buddy breathing, that is not a likely scenario. (I can imagine a tech scenario where I would have to do it because none of the other options were available; in a recent fatality in a cave, it is possible that the two sidemount divers shared their last functioning regulator, but we will never know.)

With the near ubiquity of alternate air sources, it is hard to imagine the need for buddy breathing in an NDL dive. In the only case I know of in the last decade, a woman in Florida was given a rental regulator set with only a primary second stage. As luck would have it, she ended up sharing air with an OOA diver, and they both drowned. I am pretty sure the resulting lawsuit made it unlikely that any dive operator is going to hand out a rental unit like that ever again.

This can be tied to CESA, BTW. A few years ago a prolific SB poster, an instructor, insisted on several occasions that agencies should stop teaching CESA ("blow and go," as he put it) altogether, and they should return to teaching buddy breathing instead. On two occasions, I asked him if he advocated that an OOA diver with no alternative air source available should swim around looking for a diver with no alternate second stage so they could buddy breathe rather than head for the surface. He didn't answer me either time, so I don't know what he told his students.

At the time it was the norm to use one second stage and the diver was seconds away from passing out. Of course when I gave him my reg he wasn’t going to give it back without a struggle which would have drowned both of us. So I picked up his reg and headed for the surface. You make decisions like that fast and hope it’s the right one. It worked out okay.