Water weight gain

Third pregnancy...yeah, I've done this before.  So far, this pregnancy is a little more difficult than the last.  It's not like I feel sicker.  I never threw up with any of them and I barely had morning sickness with the first, but this one feels so heavy.  He's so low in my belly that it's hard to know what I'm feeling there.  Is it gas, pee, baby?  I'm barely 25 weeks and I'm already having Braxton Hicks contractions.  It's all normal, but damn, is it uncomfortable.  Today, my tummy feels so big....ugh....