Asthma or What

Hi! I started to have breathing problems at 45. I have had breathing test, cat scans and all came back good. The pulmonologist says I have asthma. I have breathing issues all year long with no breaks. The problem is I don't wheeze and can't seem to figure out what is causing it. I know when I go o bed its worst and I feel gurgling like in my airways when I breath in and out. I feel like I'm clogging up with inflammation/mucus. prednisone helps a lot but I have to stay on it a while. I don't understand this since I never had asthma my entire life until now. And when the doctors listen to my lungs they say they're clear, but I feel the stuff moving in airways at the lower part. I really thought I was gonna die because doctors acted like I was making this up. I though about going to Denver, but to much money. Anyone else have this problem.