Q. Are my symptoms typical of an asthma patient?

Hello doctor,

A couple of months ago, I started feeling tightness in chest, shortness of breath, and overall fatigue. I went to a walk-in clinic, they did an EKG, and everything was fine. They asked me to follow-up with a physician. The nurse conducted a complete blood test and a chest x-ray, and everything came out to be normal. She still recommended me to see a cardiologist for my heart palpitations. I saw the cardiologist, and he did an ultrasound of the heart. He put a Holter monitor on me for a day. All the results came back normal, but I was still having these issues. I feel shortness of breath, chest tightness, and a heavy, dizzy feeling on the back of my head intermittently throughout the day. The heaviness is more pronounced after having meals. Because I felt a bit of reflux too, I went to a gastroenterologist, who confirmed I have acid reflux, and the doctor put me on Omeprazole twice a day. For the shortness of breath issue, I saw a pulmonologist, who said I have asthma after they performed a PFT. He gave me Corticosteroids to use twice daily, and short-acting beta-agonist in the case of an asthma attack. I have been using the Corticosteroids since four days, but I do not feel my condition getting any better. The shortness of breath comes and goes intermittently, and becomes pretty pronounced when I climb a small flight of stairs, or even when I just walk for some time. I researched more about the causes of these symptoms on the internet, and I found a few serious diseases like pulmonary hypertension and pulmonary fibrosis, which have very similar symptoms to what I am experiencing. Note that till date, I have never had a proper asthma attack. This is coupled with the fact that it has been four days, and I do not feel like the Corticosteroids are helping as yet. I am a bit anxious if I have other serious issues like pulmonary hypertension or pulmonary fibrosis. Are the symptoms that I am experiencing typical of an asthma patient? Also, considering I have done a chest x-ray and a heart ultrasound and put on a Holter for a day, is it still possible that the serious diseases would have gone undetected? Thanks.