Got my BFP but should I be nervous

Okay guys after 3 months we finally got our BFP and we are both sooooooo excited ! This is my boyfriends 1st child and my 3rd my last period was August 27th which means I should be around 4 weeks I got my positive test on Friday Saturday night I started cramping no bleeding just a bunch of white dishcharge I went to the ER bc I was panicking and they told me my HCG levels were at 584 which is reallly low so I must be 3 or 4 weeks pregnant. They couldn’t even find the baby on their US.. they told me to get my levels checked again in 48 hours so I set me a doctors appointment then

Sunday As well as today I continued to have cramps (they feel like period cramps) they come and go still no bleeding .. is this normal ? I didn’t cramp with my first 2 daughters this early