As someone who got himself addicted to dope, clean using suboxone, then relapsed and now on methadone I have some first hand account for this. I would not say you get Withdrawals after one use in the sense you experience "medical withdrawal" so if you were to get your vitals taken and compared to a daily user in withdrawal you would not have the same abnormal vitals they would. This is not to say you are not experiencing some level of withdrawal but I think what you end up arguing about is the definition of withdrawal, which is good because you are both right.
You are absolutely right in saying you wake up in a perceived withdrawal and with much of our lives being how we perceive events and not how they actually are you are in what I would call "perceived withdrawal" No one can tell you if a lack of dope makes you feel shitty and whether or not your vitals would correlate with how you feel doesnt make you not feel that way. So someone with a clip board going "look at this your a match for someone who is completely normal I say you are not in withdrawal at all" will not make you instantly feel better even if it is true.
But she is right in that if withdrawals were a medical emergency you would not qualify because in order to experience true withdrawal you must have had an active compound in your blood long enough for your receptors to adjust and create the withdrawal and in most cases change like that doesnt occur over night.
So I guess you are both right. If you wanted my opinion on it I would say just push through the bad days with out subs if you wanted to keep doing this. But the best advise is you should stop you only get so many chances before you get burned by the fire and it is much harder to heal.