Stomach suddenly soft @ 19 wks

Hi ladies, I've felt my stomach has been hard these past few weeks. There's a hard part right under my belly button, which I assumed was the uterus. About a week ago, I had a lot of bleeding and went to the ER, thinking I was having a miscarriage (@17/18 weeks). They did a detailed ultrasound & luckily, the baby is fine & they couldn't find any reason for the bleeding. We were so thankful, but I have been so anxious since...

Then this morning, I woke up and my hard stomach is now...SOFT. I'm pretty paranoid now cuz the bleeding from last week. But any thoughts or experiences re: this?

Does the uterus move???