Wonky labs even after going gf

Has anyone else had wonky labs, like low vitamins, even after being gf for a while and having completely normal antibodies? I’ve been gluten free since the very tail end of November 2024. I just had my routine blood work and some things are wonky. I apparently have low phosphorus, B12, and ferritin. However, my antibodies are completely normal. My GI is just having me start a multivitamin w/ iron for now and then we’ll check everything again in 6 months. I’m just confused how this could happen?? 😭