Tested -ve for wheat allergy but great relief to gas and lethargy and digestion aftr gluten free diet.low b12, iron ,vit d. am i gluten sensitive?

Likely: Wheat allergy is different from gluten sensitivity which requires tests like IgAtTG or genetic markers to detect. With low B12, iron etc, I suspect that you do have gluten intolerance and need to avoid all gluten. If possible get to a GI doctor since the IgA tTG is unreliable when off gluten. Avoidance and supplement for nutrient and vitamin replacement is the key.