I have that problem.
I have a rare rare lung diease that fills my lungs up with a plastic like substance. So I really do take short breathes.
I also have heart problems and a pace maker. Which heat messes with for some reason. If I take really hot showers or get in a hot tub, or stay out too long in the heat. It messes with my heart rate, and makes me chest feel really heavy and breathing hard just like you described. I also can get light headed, or pass out. Not only heat but lots of activity, excitment, laughing, anything really can trigger it.
It's not a good feeling. When you can't breath your body naturally starts panicing, and makes it worse.
Sometimes when my lungs were full I would cough so much and have no air that I would get sick, and choke, turn blue, which made me panic. After I calmed myself down, and could breath again I would cry. Many times I worried that I would be home alone and suffocate myself.
I am under 21.
I feel for you. There is nothing really to help breathing. Especially in my case. You just have to get through it. Inhalors can help sometimes. But for what you are describing probably not.
Yesterday I went swimming in a warm pool. And I got that unsatisfying breathing feeling. It wasn't fun. It also makes you tired, and weak.
I praise God I am still here though. Even if I struggle sometimes.
I always have time for a chat about breathing problems. lol. Thats one thing I have my fair share of experience about.