Braxton Hicks contractions

I'm currently 20 weeks and 2 days. Is it too early for me to have Braxton hicks contractions?? I believe that's what I've been feeling. Constant tightening of my uterus thru out the day. I have an abdominal cerclage and I'm on weekly P17 shots. I delivered my son at 23 weeks and 4 days. As time goes on I'm getting more and more anxious and scared. I just want to know that my baby girl is ok and that I'm not experiencing anything I'm not supposed to be experiencing.