My little man doesn't like to miss a beat, and his naps have gone from 4 (AM, Noon, PM, evening, then sleeping at night) to maybe 1 nap.
My nap extenders are:
I sometimes lay next to him when he is tired, and just rubbing his back, and letting my eyes close - and letting him see it. Sometimes he drops off. Sometimes he just rests quietly, and I get a few moments of rest, if not sleep.
Other times, he naps in the swing, and when he stirs, I rock it and shush him, and he goes back to sleep.
Other times, when he wakes fussing, but his eyes are still closed, I'll shush him and nurse him, and he'll drop off again.
I would stop the water - if you're breastfeeding, she doesn't need it, and yes, she will eventually take it (*Maybe not as much as you'd like but she will, honest!) Not knowing if you are using tap, boiled or bottled, it's one factor you can eliminate safely.
Not sure what your diet is, but my DS (until roughly 7.5 months) had a VERY STRONG reaction to my eating garlic, or any other of the other no-nos for breastfeeding (cruciferous, onions, nuts are the other things I avoid). The gas would tie him up in knots. Caffeine is out - and chocolate. (I thought I'd go nuts with those two! but you can do it!)
You are SO blessed she will sleep through the night. My DS stopped that about a week after Christmas. He is looking to eat sometimes 2-4 times a night. (I don't count last night - he slept through 6 hours - it is certainly not the norm!)