Anger is a symptom of withdrawal, which contradicts "too much nicotine"
The nicotine isn't the only thing smokers are addicted to in analogs. If it was, then patches or gum would be the solution to everything. some people have problems adjusting to the lack of WTA or any of the other thousands of chemicals present in analog smoke. That is why people often experience withdrawal symptoms when transitioning from smoking to vapeing.
To the OP, it does sound like the anger issue may be caused by your body detoxing from the thousands of chemicals you were giving it in fairly high quantities as a 2 pack a day smoker. Once your body adjusts to the lack of those chemicals your mood should return to normal. The amount of time it takes for people to detox varies from person to person and can be effected by things such as what you smoked, how long you smoked and how much you smoked.
As for the light headed feeling it is likely caused by either too much nicotine or mild dehydration as others have mentioned. Try a liquid with a lower nic concentration and drink more water than you think you need and you should start feeling better.