How to know if i had chemical pregnancy?

this has also happened to me, i went to get a blood pregnancy test at the hospital and it said i was pregnant but the HCG levels were kinda low. so i might have been early in the pregnancy. they told me to come back in 2 weeks for another one but when i went for the test i wasn't preggo anymore. the reason for a chemical pregnancy could have been abnormal Chromosones in the fetus, or it didn't implant correctly. it sounds like u may have had a chemical pregnancy.