Hello! Happily nursing my avid nurser - 25 month old DD. She typically nurses anywhere from 4 - 8 times per day, depending on how busy she is... and just recently has began sleeping a bit better at night, so is usually just waking 2x for nursing during the night (heavenly!). Latch-on has been painful for me since becoming pregnant, and really hasn't let up at all yet, though about 1 minute or so after she gets started, the pain pretty much goes away... I get more of that creepy-crawly feeling during night nursings, and while I don't want to "nightwean" per se, I have been encouraging DD to shorten her night nursing sessions, and cuddle back to sleep. So far, so good.
If y'all haven't yet, I strongly recommend picking up a copy of Hilary Flower's Book: Adventures in Tandem Nursing. It's a great read, full of useful information, and really has helped me feel more confident in my decision to continue to nurse through this pregnancy.
RE: upping your water intake... From what I have researched, you shouldn't be drinking tons & tons of water in hopes of increasing your milk supply. You should of course increase your water intake as you would with any pregnancy (nursing or not), but increased water doesn't coprrelate directly to increased milk supply. In fact, your body compensates for low water intake by decreasing urine output, not decreasing milk output... so I'm just trying to drink to thirst, and eat healthy, small meals often. So far, no decrease in supply... keeping my fingers crossed that supply will continue meet DD's demand.