I have chest tightness without typical wheezing. Could I be in the early stages of pulmonary hypertension?

Hi doctor,

I am a 31-year-old female. I have had pretty uncontrolled asthma for many years, and I am overweight and out of shape. I have been feeling quite a bit of chest tightness for a couple of weeks without the typical wheezing that usually accompanies the chest tightness. The tightness occurs with physical exertion (as minor as walking) and sometimes at rest. I can still walk several miles, but my respiratory rate definitely picks up, and I "huff and puff" a bit. (Nothing like gasping for air). I went to the ER last weekend to get checked out because the tightness was uncomfortable. The ECG read, "sinus tachy, incomplete RBBB (right bundle branch block), possible left atrial enlargement." My chest x-ray (including heart size) was read as within normal limits. No other comments on chest x-ray. All blood work was normal, including Troponin and pro-BNP (brain natriuretic peptide). My O2 saturation was 99-100. The last time I checked BP, it was 125/77. I was discharged with "atypical chest pain" and given Ipatroprium and Albuterol for nebulization with Flovent (Fluticasone propionate) 44mcg two puffs twice a day. I was worried about the ECG, so I followed up with my PCP, who repeated the ECG. This ECG did not show possible left atrial enlargement or IRBBB, but it read "borderline ST-T changes in the septal leads for sex and age." My PCP said this was an overread by the machine, and he considered it a normal ECG. However, I relayed my concerns to him about the shortness of breath with exertion, and I am really scared of potentially having Pulmonary Hypertension. My rational brain tells me it is unlikely (despite being in the prime age and sex for idiopathic pulmonary hypertension) because it is a rare disease, my chest X-ray was normal, my ECG shows no right heart strain, right ventricular hypertrophy, or other signs of pulmonary hypertension, my resting heart rate is 69-71 according to my fitness band, 02 at rest was 99-100, I can climb four flights of stairs (heart rate gets to 135 doing it, but I can breathe), I can walk for miles (with some huffing and puffing and heart rate in the 110-120). No dizziness or fainting. No lower extremity swelling. My PCP said my heart sounds fine (no extra heart sounds) other than what sounds like an innocent murmur. He has referred me to a Cardiologist for peace of mind, but I am still pretty frightened I will be diagnosed with this condition. Do you have any insight? Could I be in the early stages of pulmonary hypertension? Or perhaps my chest tightness or breathlessness is better explained by my asthma (even without wheezing), being out of shape, or anxiety? Any insight would be greatly appreciated. Thank you so much.