Am i expecting twins?

right now i'm 4 weeks and 5 days pregnant. i got my BFP at 9dpo, at 10dpo i got my hcg level tested and it came back as 39, at 17dpo i got tested again and it was over 1800!!! my doctor added up that my hcg levels double every 30 hours!!! i'm just wondering if there is a chance of twins???? My mum is a twin and i do have twins on my dad's side too.