Peak Flow Question

Patient: I went to the doctor a few days ago for really like I couldnt breath, so she gave me an inhaler and a peak flow meter. The book that comes with the meter says my peak flow should be 460 I’m blowing 230 and feel like I can’t breath so I took my inhaler and afterward I’m blowing 350 and a little bit shaking. is this normal?

Symptoms: Coughing, tight throat and chest, hard to breathe