Positive antibodies RH-

I had my 10 week appointment last week and everything was good with baby #3. I got bloodwork after and they just called me to tell me I need a titer test because my bloodwork came back positive for antibodies. I am RH-….I had my second baby 7 months ago. I remember getting the rhogam shot 12 weeks before my c section. I hemorrhaged pretty severely and had to have several blood transfusions. I also remember them giving me rhogam after the c section. I don’t understand how I’ve tested positive for antibodies?? Could it be from the transfusions? I’ve had 4 miscarriages and two babies and I’ve always gotten my rhogham shot well within the time frame I needed it. I’m freaking out 😭😭