Spasms and/or flutters in uterus

So over this past week I have felt dramatic spasms or fluttering in my uterus. This is my 3rd pregnancy (actually my Rainbow baby) and never felt anything like it until later on, like second trimester with my daughter and the one I miscarried. As of now I'm 6w5d and I'm just curious if anyone else is feeling the same?? I've read a bit and some said, obviously, it could be gas (but it definitely doesn't feel the same) or that it could be the uterus expanding or possible twins? Just extra cautious because of my precious pregnancy....and of course curious.