Kathryn, I'd suggest you pick one plan (check the "Which low-carb plan is right for me?" link to your right, under the Quick Links sidebar), read the book, and stick with it. You'll find most of your questions answered in that book.
Since most plans have slight differences, you'll drive yourself crazy if you try to take one thing from here and another from there.
Drinking water is crucial. That's one thing people agree on. The general rule seems to be 64 ounces a day (that's 8 8-ounce glasses) PLUS another glass for each 25 pounds you are overweight. (A simpler formula is to divide your weight in pounds by 2.2 to convert it into kilograms, then drink one ounce per kilogram.)
For calories, they do count, and most people would advise you to aim for 10-12 calories per pound. Eating less (and not drinking enough water) could hinder the diet.
If you're feeling better, then low carb probably is for you. I can't help on why you've gained four pounds -- I can imagine the frustration. (I saw your post last night, and perhaps the reason no one's responded so far is because no one has come up with an answer. You'll find that people around here are generally very helpful.)
Give it another two weeks. Pick a plan and stick with it. Weigh on the same scale at the same time of day once a week. OR weigh every day and average your weights at the end of the week. It is possible that if your start weight was taken at the beginning of the day, you would weigh four pounds heavier at the end of the day. Also, the weight of your clothes may make a difference.
Read through some of the journals herre. You'll find struggles and successes. But it's hard to read these jounals and still have doubts that low carb doesn't work
Good luckl!!!