Your betas look really good and it's true that symptoms don't necessarily prove the wellbeing of the baby, but the probabilities are also on your side, and it doesn't seem like you have any bad symptoms like bleeding or cramping so there's no reason to worry as well. I was really freaked out for a long time because of how many MMCs there were before the first scan. When I was at the first ultrasound and they took my blood pressure, my own heartbeat was way up and the doctor kept telling me to relax but I couldn't because I was so nervous. Then even when the baby came up to the monitor, I was still nervous because it's possible that the heartbeat may not be normal or something. It was only after she measured the hb and it was normal, that I really relaxed.
I'm still anxious every time we go for a scan. For my 12 week one, the baby came up but wasn't moving at the moment so I felt like I was holding my breath when the tech measured the heartbeat. I'm anxious when I look at my bump and i feel like it's not growing very much, and other people are already feeling a lot of movement but I'm not etc. I was anxious that my genetic screening numbers were not AS good as I want them to be. Then I started reading about stillborn births and feeling worried about that happening to me. Trust me, there's always something to be anxious about, the important thing is to learn to deal with it. Take it a day at a time, and appreciate what you do have at the moment. After the first ultrasound, I told my husband, no matter what happens later, I'm just glad this bean existed at all and that I was able to meet it. And I've said that with every milestone.