21 weeks 4 days

Abby • 33 years old. Married to Eric. Mom to 2 boys that are 3 years old and one year old!
Okay so I'm 21+4 and still haven't felt my son move. I do have a tilted uterus and anterior placenta. I heard his heartbeat on the doppler at 138 about 30 minutes ago so I'm not worried about him just wondering if it will happen soon or maybe I have felt him and thought it was gas? Any insight would be helpful!