Keep with it! Starting is always one of the hardest things to do, and sticking with it for the first few months is the next hardest.
This may sound stupid, but I've had people use different scales and wonder why they varied so widely -- not all scales are calibrated correctly, so stick with one and only one.
Also, start using a tape measure and progress photos. If you can, start taking body fat measurements and pay less attention to the scale.
I can fluctuate 5 lbs on water retention and daily diet easily, and I'm a
guy. I'm told women can fluctuate as high as 10 lbs, due to hormonal factors added in.
You need to measure progress over time -- I'd say a minimum of 4 weeks. I would say that if after 8 weeks you don't see progress, then you definitely
must re-evaluate your diet and exercise program.
When asking for advice, it helps if you post details like dietary intake (via TheDailyPlate.com or similar sites) and details on your exercises.
For example,
here's my food diary. (Not updated since February, sorry!)
And here is how I would describe my fitness routine:
Cardio: I'm doing Week 6 of the
C25K running program this week (3x a week). I run at 6mph with a max heart rate of 180bpm, and walk at 4 mph with a HR of 130bpm.
Weights: I'm following the
Stronglifts.com 5x5 for beginners. My lifting stats are 190lbs for the squat, 205lbs for the deadlift, etc.
In general, if you're following a set program you can link to it -- otherwise tell people what you're doing, for how many minutes, and how intense it is (in terms of heart rate, speed, weight being lifted, or whatever is a good measure of intensity). You'll get much more specific advice and quickly this way.