Why would i have moments where i become extremely tired to the point of drifting off even though im taking iron and b12?

Hard to say.: There are many causes of the sense of fatigue you describe. Too many to explore here. You correctly note that iron and B12 supplementation does not generally treat fatigue. See your doc for an exploration of your symptoms.

Re-evaluate: If lying down, putting your feet up and drinking a rehydrating solution with a small amount of sugar makes you feel better it could be low blood pressure. You could eat 6 equal meals, avoid tobacco and alcohol, move for 30 seconds "pretend jump roping" without jumping but stepping over the "rope" from arms moving in circular motion like the "rope" every 10 minutes using a kitchen timer.