I found out at 15 weeks, at my first sonogram. Though we had prayed for more than 10 years that God would give us a son first, then identical twin daughters with blonde hair and blue eyes.
There were a couple of earlier things that made me suspect our prayers had been answered: 1) I was charting my cycles, so I was amazed by days 5-7 post ovulation that my temp was three times higher than usually was when it leveled out after ovulation!! (1.5 degrees higher instead of 0.5). When it began climbing again 3 days later, I knew I was pregnant and already wondered about twins... 2) The week before my sonogram was my first OB visit. With the yellow tape, my fundal height was 23 cm. That meant when I was 14 1/2 weeks along, I measured the size of a 23 week pregnancy, nearly 9 wks ahead of normal! With my first, I was always right on track.
edited to add: Oh, but I've not gained much; right now I'm 24 weeks along and have gained not quite 14 pounds.
I can't wait to hear what you find out this week!!! Good luck!!!
And, that is SO AMAZING that you and your brother were twins! It's sad that your mother never allowed herself to properly grieve. I would definitely start doing some research about the details, whether the twins actually miscarried and were expelled or if they were reabsorbed, etc. Two weird stories:
1) It was in the news recently that a mom found out after needing the whole family's DNA checked for a match to one of the children's illnesses... that one of her children didn't even have her DNA!!!! After researching, they figured out that she had been a twin and that the vanishing twin's DNA was in the egg that made that child, instead of hers.
2) A friend in my homeschooling group is right now in Maryland as her daughter (10) goes through her 10th surgery to correct gyno/urinary malformations that were evident at birth. When I asked her the details, I was fascinated to learn that the daughter had been a twin... The twin died (at 12 weeks) and was reabsorbed. But her daughter ended up being born with two uteruses and two vaginas! So they have done multiple surgeries to correct it. She hasn't told the daughter yet that she was a twin, but plans to once it's all fixed and behind them; then she will know why all those surgeries were necessary.
I even heard one doctor speculate that a MDC friend with lots of moles all over her body may have had a vanishing twin, and that the moles are actually parts of the twin that didn't absorb completely. Isn't THAT freaky!!!?