you may be able to go for an ultrasound now if you girls are seriously interested in finding out. You can go direclty to a private clininc for an ultrasound- you just have to pay
I found out i was having twins at 6 weeks, 6 days via dildo cam at my FS office
so anytime after 7 weeks you should be able to see how many sacs, just may not be able to see heartbeats yet.

good luck
keep us posted