I'm having trouble breathing, but I'm unsure as to whether or not it's asthma?

I can be sitting, standing, working out, but sometimes I feel like I can't breathe.
I'm taking in as full of a breath as I can, but sometimes it just feels like no matter how much I breathe, I can't get enough air in my lungs. As though something is pushing against my chest, not allowing it. I don't feel any pain when this happens, but sometimes I freak out because it lasts longer than a few seconds.

I'm starting school soon, and I find it embarrassing. I don't want to be sitting there breathless in class.

I've told my mom, dad, uncle (he used to be a doctor), no one knows what it is. My brother used to get it a LOT when he was my age (I'm fourteen). He's told many doctors, who don't know what it is.
Sometimes I just start panicking and crying, which makes it worse.

I feel like I have to start yawning to get the right amount of air in my chest.

It's so frustrating!

I don't know what this is! I want to ask my mom if I can see a doctor about it, but half of me knows she'll say no.

Taking long, slow breaths just makes it worse.

Some days it doesn't happen at all. I can go weeks without it happening. But it's been happening so much lately. Hourly, for about the past week.

I used to have the same problem when i was about 12, it went away...
Whenever I breathed, my lungs just didn't have enough space for them.
I think it's a part of puberty, but you should definitely ask a doctor.
But yes, the symptoms of asthma are the same.

This has nothing to do with puberty!
It may be something like asthma or pneumonia.
But you need to tell your mom you really need to see a doctor.

Could be anxiety