Low hcg so worried at 5weeks 4days

Hi this was my first fresh transfer 3 weeks ago today on 2/17, march 4th was my first beta and my number were 234 so today my doc looked for a sac and couldnt see any, he then sent me for a second beta, the number was 1400. My doc said this is not a level he wished for so saturday is my third beta. According to him it should have been around 4000+😭.

What do u think? I am worried sick. My symptoms seems to lessen too🙈 for the past couple day. Is there anything to worry or levels are fine? Please share ur experience thank u