High heart rate during pregnancy


I've had a very high heart rate since I was about 12. I suffered severe anxiety as a child and had panic attacks. I've been tested extensively for the heart rate but nothing has ever been found so I came to the conclusion that it was my anxiety and that I was just in a constant state of panic. I've been on beta blockers before but they lowered my blood pressure too much which made me dizzy. Now I'm 4 weeks pregnant and my heart rate is more consistently high than before and I'm very dizzy whenever I'm standing. My doctor suggested going back on beta blockers but I'm concerned about lowering my blood pressure too much or the medication harming my baby, but I'm also concerned about my high heart rate and anxiety harming my baby. Has anyone had a similar experience or could weigh in? Thank you.