First initial viability sonogram

Alex • Expecting our first baby on December 1, 2016 and loving every moment of pregnancy and the final months of just us <3
At four weeks I was confirm pregnant at my OB, but the first ultrasound didn't show anything, he didn't say anything was wrong and not seeing a sac is normal for that early.
My next ultrasound, internally, was April 26 when I would be 8w3days, but they called and moved my appointment up to April 19 at 7w3days- I'm nervous I won't be able to hear a heart beat or see anything. 
Does anyone know if I'm good or had a sonogram done this early?!?