Pregnancy Question

Hi, moms. I have a few questions, so I had anemia before my pregnancies but it just wasn’t as bad, I’ve had one blood transfusion and one iron infusion. My doctor put my on Ferrous Sulfate due to my hemoglobin being low. I’ve been taking for a while and no results. I’m having all different kinds of symptoms, lightheaded, weak, heart racing, losing focus, nausea, and dizziness. I’ve even fell just recently due to being so weak ( Im 24 weeks and 3 days ).. I have an appointment in the morning for my doctor to check my hemoglobin again. Has anyone experienced something similar? What did you doctor do for you?