Irregular Gestational Sac

Amy • Wife and soon to be Mommy to Olivia Rae Flores 💕
Hey guys! Congrats to everyone! I just had a question to ask you guys. This is my first pregnancy so I'm super excited and also a nervous wreck. Anyways, at my second ultrasound I measured at 6 weeks but they said that my gestational sac was irregular. We heard the heard beat but it still scared the crap out of my husband and I because they said that it usually leads to miscarriage. They had us go back in 2 weeks (the longest two weeks of my life) and baby was there and was growing and the heartbeat was strong. But, still the sac was "a bit irregular". Does anyone have any advice or any knowledge of this? I'm so happy baby is good but I'm still a little worried. Not really sure what to think at this point. Thanks guys! I'll add some pictures of my last two ultrasounds below... 
This was when I measured at 6 weeks and when they gave us the scary news
This was my last ultrasound. Baby measured at 8 weeks 2 days. Sac is still "irregular" to them..