Multiples?

Is there any way to tell if youre having more than one baby before having a scan? Like would you get a very dark line fairly early? Would your levels multiply like crazy? Early pregnancy symptoms? Or maybe there is no correlation. I'm just curious i feel like im extra pregnant and im still super early. We have nearly a dozen sets of multiples going on my dads side. I got a very dark positive a day before my missed period. And my levels are really high and im about 5 weeks. I'm also really nauseous already and my sense of smell is ridiculous.