Two things... pounding in my ears and how do I change my due date on here? I did it wrong.

I have extremely low blood pressure and irregular heart beat/palpitations when pregnant. Usually, I have a three specialists besides my obgyn. This pregnancy... I'm having difficulty with doctors and medical personnel! So, I was told they can't fit me in to see my obgyn and I should go to the ER or clinic to be seen about the throbbing heart beat pounding in my right ear. The issue with that is the wait is hours before being seen, I have children to get off to school in the morning, and the ER staff acts as if I don't know anything about my body, pregnancy, Lupus complications (which very few of them have even heard of!) . My question is... have any of you experienced this and should I go to the ER tonight or wait? It is NOT high blood pressure... mine is 90/50 lately. Which is only a bit lower than my norm this pregnancy 100/60. Waiting to see a new doctor. So, I'm feeling like this was the symptom they put me on the necklace heart monitor for with my two oldest. It was just 8 years ago and I can't remember! Any advice? I apologize for such a long post. Also, how do I change my due date. It is one week off from my actual due date.