Hi try not to worry and diffidently change nurses 4under3 your under enough stress worrying about this with out having to cope with an insensitive nurse i don't want to scare you but i would ring your doctor and see if you could bring the scan date forward for your peace of mind ,at this stage it could be the placenta and also bleeding could be caused be a varicose vein in the cervix so take it easy oh and its very common in twins about 3 out of 5 would have bleeding expecting twins and go on to have healthy babies.
i had bleeding in my first pregnancy it started at 6 weeks and went on for nearly 4 weeks but the baby was fine i had morning sickness was so tired all the normal symptoms , on my second baby i had bleeding at 9 weeks again went for a scan all was fine and it only lasted a day this time, on my third i had none. i did have a miscarriage in between my first and second but the bleeding came with a lot of pains and it was exactly like labour pains it was over in a couple of hours and i passed loads of clots sorry, but i did discover i was 9 weeks pregnant a couple of weeks later it looked like when i was losing one i had one making its way to the womb hope i don't upset any one with that just so you know the difference. but good luck and try not to worry both of you let me know how you get on and take it easy
niamh