Alam ko mama, ang anxiety talaga pag first pregnancy at may ganito, pero ang palpitations mo right now ay maaaring dahil sa stress at hormones na sobrang taas ngayon, a few of us went through the same thing and it really helped na nag-relax kami once natranslate namin yung ultrasound sa sarili namin na "okay lang mag-antay." Since your OB is being cautious at continuing your meds kaya probably she sees something promising pa, I'd really suggest bringing up the heart palpitations with her sa next visit kasi hindi dapat mag-ignore ng yan during pregnancy, pero breathe mama, maraming success stories din ng blighted ovum turned out okay through monitoring like what you're doing now!