What do you mean she couldn't suck hard enough? My dr has advised us (& pharmacy) you spray the ventolin once, take 4 breaths. How many puffs were you told to go up to? You may need to use 2-3 puffs & use it every 4 hours to help. I personally would only use it 4 hourly if coughing fits are happening.

ETA:- my husband has just had a month off with pneumonia. Take care!