Chemical Pregnancy OR miscarriage???

Got my BFP after 2 1/2yrs TTC with 2nd IUI... I experienced spotting on weeks 3 and 4 HCG levels kept rising and ultrasound showed two sacs attached to iterus (one smaller than the other). Doctor explained spotting is common when pregnant with multiples and HCG levels were fine. Today I went in for my 6 week follow up only to find my uterus is empty 😔 I was told it was a chemical pregnancy but I have been reading that only happens when pregnancy is only confirmed by HCG levels however, doctor detected 2 sacs on week 4... was this a miscarriage? Is there a difference? ..::sigh::.. How soon after your chemical pregnancy did you conceive again?...