I am on the same boat, feeding on demand and he feeds nearly every hour and a half! Completely normal, my bubs is only feeding for around 5-8 minutes at a time. But seems to do 3-4 hour stretches at night so I am assuming he is getting as much as he needs. Watery poop is complete normal also for BF babies!
I was told to avoid pumping because it will make you more engorged and make more milk. Only take the top off to be comfortable if you are super uncomfortable, your milk will regulate fully by 6 weeks, but quicker if you let baby sort it out for you