Am I more active than I thought?

I checked sedentary when I started this site, because I figured I didn't engage in a lot of exercise. When I do exercise, I log it in. I have lost weight so far... But it has been a struggle. One pound loss, 2 pound gain... Up and down. I started running a couple months ago because i hadn't been losing weight... and gained weight instead of losing. So I increased my calories from 1200 to 1270 by checking off that I would like to lose 1/2 pound a week instead of 2 pounds per week. Then I started to lose again. Well, the past 2 weeks I have not been able to run as much because it has been raining and I run outside & sometimes have to bring my daughter with in the jogging stroller- which wouldnt be appropriate in the rain. Since I have not been running as frequently, I gained 3 lbs. I keep telling myself it's water weight because I have not gone over my calories (despite feeling so hungry because I am used to getting the extra 250 calories a day from running), but would water weight stay for TWO weeks? Doesn't our metabolism speed up as we exercise & build more muscle? I also have a two and a half year old that keeps me busy all day, and am a wife (so constant picking up & doing dishes, laundry, etc.) and I am a full time nursing student (includes walking on a large campus & on my feet for six hour shift during clinicals at the hospital). So I am wondering if this classifies me as "lightly active" as opposed to "sedentary" and if this could be the cause of my weight loss turmoil. I love that overall the scale has gone down over the past three months... But it's been a constant struggle to keep it down and it shouldn't be this hard when I am doing everything I am supposed to in regards to calorie counting and weighing my foods & exercising. This 3 pound gain the past two weeks has really got me in a bad mood. I only missed my daily run 5 days out of the past two weeks and I can't believe that made me gain so much weight! I just don't think it's supposed to work like that. Any input is appreciated... I did not eat anything abnormal during this timeframe- no overages in sodium or anything and my water intake stayed the same.