Terrified of blood taking in pregnancy! 😨

Let me just say I'm not afraid of needles or the pain of having blood taken- which to me isn't painful at all. I just had my 12 week bloods taken for NT and the woman kept pushing the air back in my vein as she was withdrawing I'm assuming to get more blood into the needle? For years I've been terrified of someone accidentally injecting air into my vein... I don't know how to get over it 😨