Ultrasound glitch or disappearing twin?

Akemahs • Solo parenting again...tear

Just found out that there is a such thing as vanishing twin. & i was just wondering if thats what happened in this ultrasound. I was 6w in this ultrasound taken on 2/10. My nine year old pointed out that it looks like a upside down smiley face. After looking at it now it looks like a empty sac.

I had a little brown blood come out 2/26 but it stopped as soon as it started. Doctors couldnt really explain why the bleefing occurred. But the 2nd picture is of the following ultrasound at 8w.

So what you guys think? Was something possibly in there? I go to the doctor tomorrow & ill ask there too. Just curius.