HCG Bloodtest

So I went and got labs done today but they didnt come back as expected. I know that my pregnancy test is positive so I'm not understanding why my HCG came back so low. It was only 2.4miu could it possibly be because I am earlier then I thought or is it that I am probablyhaving a chemical or miscarriage? I really hope thats not the case and this turns out differently and my tests get darker and HCG goes up. According to my app it says I am only 4w2d today so I'm confused but still hopefulit will turn around in the next few weeks!