Everything that I have read says you should start feeling your baby move between 18-22 weeks. Well I am 21 weeks and 3 days and I am still not sure if what I am feeling is her moving around. I really think that it is but it is not the feeling of "butterflies". This is a new feeling (and it doesn't feel like gas) that I am having so I am just going to say that it is her.
So it is definitely her I am feeling. Around this same time (10:45 am) yesterday I was feeling the same thing. So today when I felt it I started paying attention. Then I started poking her back when I felt her poke me. She would poke me back again...and my stomach would move outwards! Pretty cool!!! I think I wore her out or bored her because after about five minutes she stopped playing with me.