First appointment- too early...

I had my first appointment today and the dr did an ultrasound. He found a yolk sac, but was unable to find a heartbeat. He thinks it's probably too early... I got a bfp on April 30th, but haven't had a period since my first baby was born in march 2009. Without a period, I had no idea when the new bean was concieved, so they made me the soonest appointment. But it looks like I was barely prego when I tested. So still no due date, but going in again for another ultrasound June 3rd, and hopefully we'll see a heart beat then!