HCG levels low

So I had blood work done 2 days ago and just got a call back from my Dr to say my hcg levels are low (roughly 500). I'm 6 weeks today - so 5w 5d at the time blood was drawn. She told me to come back next week to check again (hopefully the number is higher), but I'm just wondering if anyone has had a lower number and been fine throughout the rest of their pregnancy.... this will be my first so I'm hoping my little bean sticks but I will admit I had a little cry in my office when I hung up the phone. My partner and I have told his mum and two of his siblings, but are unsure if we should tell anyone else this weekend like we planned to.