Not to scare you, but I bled. I began spotting at 6 weeks and went in for an ultrasound to confirm a miscarriage where they found two healthy heartbeats instead. The bleeding subsided within two days of onset and then I just worried for the next month and a half.
I have heard that spotting is not uncommon in multiples and it has something to do with implantation. Many women who experienced the bleeding describe it as slight, brown with no other symptoms like cramping. Most women mistake this as a weird period.
I am not saying this is what you will experience... please don't think I am trying to scare you. I am currently 26 weeks with very healthy identical boys. Of course I did feel heightened pregnancy symptoms like bloating (I mistook this as showing early), emotion overload, early morning sickness, etc... but I think this would be difficult to detect for a first time mama.
Keep us posted! Whether there is one baby or a litter in there, being pregnant is a miracle we must revel in. Congratulations and best of luck!