Low hcg compared to previous pregnancies

Mary • First baby born May 2020 Baby #2 due April 2022

Has anybody had very different hcg levels through different pregnancies? I got my hcg levels today and they are only 3,255 at 5w6d. My last pregnancy they were 51,600 at 5w5d! I’m so nervous. I’m also having a little bit of cramping on my right side, so I’m scared this may be an ectopic pregnancy.