Afaik
There is no exception to the National Minimum Age Act as it is written.
If you read the act is it very specific in what it outlaws. So there are some loopholes which vary by state (some states didn't close the loopholes with their own legislation). There may be some wiggle room in the phrase "publicly possess". And you'll notice the act doesn't say anything about consumption (though most states have laws which outlaw consumption as well). Try contacting your states Attorney General's Office for specifics.
I don't know what your license looks like, the doorman shoudl read your birthdate. If you're under 21 the laws still apply. Call your AGO to see what the loopholes are.
Ibis