Twins would be so fun! Early pregnancy is terrifying, especially if you've tried for a long time and/or had a loss. When I found out about this baby, I didn't have the feeling of doom like I did with my 1st pregnancy. All my numbers were good. Then I had bleeding. Two episodes of bleeding between about 6 and 8 weeks. I was so scared of losing another baby. I had 4 ultrasounds by the time I was 9 weeks, and all they could say was I had some fluid in a cul de sac but everything with the pregnancy looked normal. Fluid there usually results from an ectopic pregnancy, and I'm pretty sure I had 2-3 eggs when I ovulated, so I guess it's possible I had an early ectopic that resolved itself along with the intrauterine pregnancy. No way to know for sure.
My only advice is to try to stay positive and enjoy each day as it comes. You'll feel better with each little pregnancy milestone, but the fear never entirely goes away. I guess that's the way parenting is, though!