If there is slight bubbling in my uterus does that mean I'm pregnant? or is that normal?

I am 17 and freaking out because I keep feeling these little ripple type things in my lower abdomen/uterus. I was worried about being pregnant but i took a blood test after 2 weeks and it was negative. Is it okay for me to be feeling this like could it just be gas? Cause I'm slightly freaking out