Weight is a worthless measurement. Go by how you look, feel, and perform. Or how your clothes fit. Read this: http://everydaypaleo.com/2011/06/22/attention-scale-addicts-part-2/

My body weight can fluctuate 3-4 pounds from day to day (although I am somewhat larger than you and a male). If you're looking better, don't sweat the scale one bit. Eating more protein alone (without increasing strength training) can help you build more muscle if your previous diet was low in protein. Sounds like you know what you're doing. Keep up the good work!

It might not be related to calorie intake at all, but at your age you may still be growing/developing. I had the usual puberty-type thing when I was a young teen, but practically had the body of a 12 year old boy until I was about 22-23. Then BOOM! Baby got back! And grew 2 cup sizes! I also grew almost 2 inches taller, my feet got a size bigger, and weight gain of almost 20 pounds but most of it in the nicest of places. (If I'd been the working out sort back then, it might have been all to the best places.) All that happened within less than a year, so at the time I freaked because it was was pretty quick and I wasn't expecting it.

So if you are on the petite side when it comes to hips and bust, it may just be your time to get your voluptuous on! Going Paleo and eating healthy amounts of fats may be balancing out your hormones if they were a little low before.

I know telling an 18-year-old lady not to worry about her weight is futile, from experience, but it sounds like you're at a healthy weight for your height. :)

I'm 45, female, and was significantly overweight when I started paleo in January, and am still overweight. If I go by the scale, my weight loss has been agonizingly slow.

But at the same time, my body comp has definitely changed--I noticed very early on that I was gaining good muscle definition in my arms (which were kind of skinny-flabby before), even though I'm not formally working out. My "exercise" routine mostly involves walking to the stores/post office, digging in the yard, doing heavy maintenance chores and making DIY improvements on the house, and shifting heavy items around unassisted (such as getting the old water heater out of the basement all by myself when the big, burly plumber whined that it was too heavy and not part of the installation agreement and I'd have to pay extra, even if I helped him. But I digress.).

I haven't changed my activity level very much, and am not intentionally doing more heavy lifting, but my arms sure look like I have been. I even started wearing sleeveless tops this summer because I finally have nice arms! So the increased muscle density is probably offsetting the fat loss as far as the scale is concerned.

My fat distribution has also changed in interesting ways. My fat ass has not only shrunk, but it's nowhere near so lumpy-looking as it's always been. While it's still fat, the shape of it is much nicer and rounder--and I don't ever remember it looking like that before. In fact, I think I could even wear a swimsuit without feeling terribly self-conscious about it because for a fat ass it looks pretty good.

So the scale tells me one thing: "You're hardly losing weight at all." But the scale is a notorious liar. My body--this thing that actually matters--is telling me a very different story.

You're a lot younger, and were already at an ideal weight when you started, thus your changes in body comp toward more muscle may be showing up as weight gain for you. So the advice already given--to look at how your clothes fit, and how you feel and perform--will probably be far more useful (and less crazy-making) to you than going by what the scale says. Because the scale lies.

I'm female and close to your age (22) and my weight fluctuates wildly from day to day. In one week it went from 122 to 114 - and this was a week of Paleo eating with no attempt to restrict anything. And then it went back up to 119 the next week, again for no apparent reason. I wouldn't sweat it. Judge by how you feel and how you look, not what the scale says.