Struggling with Hashimoto's Symptoms

I’m not sure if it’s from my hashimoto’s or simply myself overthinking. but i haven’t been doing too well. i can’t stroll around the park or my neighborhood without having to take many stops just to gasp for air. even when i only taken 10 steps i feel like i’ve ran 10miles. if i feel a little too warm i just start feeling faint. i take care of myself i eat and drink what i’m suppose to. but even know i’ve developed sleep apnea and won’t wake up until my hearts beating aggressively against my chest. is this normal? my endocrinologist said i had a healthy thyroid (though if i have hashimoto i don’t think it’s all that healthy.) i just don’t want to burden my doctors with this fear of mine if it’s just normal symptoms. i’ve been doing this solo for a little bit. i turned 18 in february after my second biopsy so this is all new to me. im sorry for this, i just don’t want to feel alone in this.