Can barely breathe and heart palpitations?

Before I start, I have asthma and yes I’m already seeing a doctor for this but with no results:

I’m a 20 year old girl with a BMI of 27.5, if that helps. 

So I’ve been having heart palpitations for a bit now. Normally they start at night when I’m sleeping because I stop breathing. So I’m being tested for sleep apnea. 

But on top of that, I haven’t been able to breathe well AT ALL for the entire day, which has been going on for months. 

When I breathe I get a weird pressure-like feeling in my “throat” near middle of collar bone, and near the heart on the left chest. 

I’ve had to start mouth breathing almost 24/7 because of that, and even then I can barely breathe. 

I constantly sound like I just ran with how heavy I have to breathe. 

I got a new inhaler that’s stronger but it doesn’t do much. 

Does anyone have any idea what’s going on?

I try to exercise and I just get bad heart palpitations and I’m too scared to keep trying because I’m unsure what’s happening. 

I’ve also cut out any coffee which seems to help more but not all the way

Heart races when I bend over

Hard to breathe, when it starts it’ll last for days with no letting up

Heart racing at rest

Palpitations at random, laying down, falling asleep or with very minimal exercise like walking down the street or shopping

Heart flutters at rest or just gg from walking/shopping