I don't know if it's normal for everyone but I had that issue too. I could smoke ounces and I'd barely get a wheeze but .2g in the vaporizer would have me coughing up a lung LOL
There's a learning curve; I've had better luck with different vaporizers too.
Take 3 or 4 puffs of CBD vapor without any THC content first. The THC is very harsh and your lungs don't like it. Then try the THC. After the THC take a couple more puffs of CBD. Medical cannabis has been the answer to my chronic migraines. It's the only thing that has helped. Good luck!