Finding baby’s heartbeat

Ok so since I was 8 weeks or so the nurses and doctors have had a really hard time finding the babies heart beat. I mean like 2 or 3 different people come in to try at my last appointment they almost put me on an ultrasound to see if they could get it that way! The last time I was there the doctor said that the baby was hiding behind me which makes it difficult to locate. idk maybe it’s just me but it just seems fishy that they can never find it plus I’ve been having these weird vivid dreams that I’m pregnant with twins and that’s the reason it’s so hard to find it lol but I’m just crazy like that lol but has this ever happened to anyone?!