Hello second trimester!

So excited! Today is the first day of my second trimester! I have my 2nd prenatal appointment tomorrow. I have a few questions and minor concerns that I though I would ask you ladies. At my first appt. @ 8 weeks the midwife was unable to hear a heart beat. I'm a larger framed woman around 215lbs. Is this normal?? She said if we were unable to find with heart tunes we would do an u/s this time. Also I'm so anxious to find out the sex of the baby. Have any of you found out this early? With my first child we didn't have an u/s until 17 weeks.