Please make me understand my checkup rep

Hello doctor, I had gone through full body checkup and findings of the report's are below mentioned - : 1.IN thyroid profile total test A) tsh ULTRA( 0.23)is low while B) t3 & t4 are normal 2.In iron studies basic report A) iron serum(23.0)is low B) transferrin saturation(7.88) is also low 3.B12(93) deficiency 4.vitamin D (12) deficiency 5.IN glycosylated hemoglobin report estimated average glucose(eAF) is low [73.84] Besides that I have growth issue like since last 7-8 year's I had no growth in height, weight, muscle etc Infact my weight kept on decreasing all the way. Current status: I'm 24 year old, height= 168cm, weight= 43kg, BMI is underweight with score below 17 + super skinny. In light of above mentioned concern please guide me for further follow up, diagnosis and treatment.