Anyone having issues with heart palpitations?

I'm due June 27th, so I'm currently 14+4. I've been having heart palpitations since around 6 weeks that are pretty scary. I was diagnosed with sinus tachycardia a few years ago and currently take a beta blocker to keep my heart rate low, but since I've been pregnant I've had these episodes where I'm just sitting not doing anything and all of a sudden my heart rate jumps up to somewhere between 100-120. Without the beta blocker it would go up to the 150s. I went to the ER several times since this would make me really dizzy, had some chest pain and I got scared, and every time they told me my heart was ok just beating really fast and it would go away in a couple of hours on its own without any additional medication. My EKG always shows a good sinus rhythm, just sometimes it's really fast. I saw an electrophysiologist a few days ago and he said it could be from the pregnancy hormones and it's not life threatening, just really uncomfortable. He thinks it should go away after I give birth. My cardiologist also thinks it might be a little bit of anxiety too. Anyone else having this problem or had this problem with previous pregnancies? Hate going through these scary episodes!