Fetal dopplers

I want one. I don't want one. I don't want to not be able to find the heartbeat and freak out. But I literally have panic attacks, because I get so worried something is going to happen to my baby. My last doctors appointment was at 16w3d and my little peanut had a heartbeat of 153. Today at 19w, I am just freaking out because I'm not showing and I don't feel movement(I don't think.) could someone give me advice on fetal dopplers??