blood test results

I had a BFP on Tuesday and went to my doctor on Wednesday to have blood drawn to be sure. I was exactly 4 weeks on Wednesday so I'm still very early but I got the phone call this morning that my blood work was positive but my HCG levels where very low so there going to retest in a week to be sure I am pregnant... I can't help but freak out about this after getting excited that I might be growing a human, ya know? 😞 has anyone else had this happen??