Stop. Breathe. Relax.

3lb in 3 weeks is not nothing. That's a pound a week and is generally accepted fat loss rate. This is good.

All the "great results" you hear of people seeing double-digit scale losses in a week's time are losing water weight, and even the people losing 3+ pounds of fat a week are 400 pounds to start with.

In fact, that same water weight is likely what caused your "gain" that you saw on the scale. Hormones still fluctuate, too, and the female hormones aren't the only ones that can cause water weight gain. Cortisol is actually another big contributor, so your stressing over it is actually making matters "worse."

According to your ticker, you want to lose about 25lb, and from the looks of your profile picture, even that much seems pushing it. In other words, you don't have much to lose to begin with. This is also a good thing, but it does mean that you won't see the big number changes on the scale. That's okay.

Don't starve yourself, either. Work out how much you should be eating for a minor deficit (no more than 1lb per week) and strive to average that over the course of a week. Do LCHF for the health benefits, and the fat will shift as a byproduct.

Also, consider doing some strength training. Weight lifting is phenomenal for preventing osteoporosis, and muscle mass will help further reduce body fat. (Just keep in mind that strength training will mean the scale won't always move down. That's okay. The scale is only a small part of the picture.)

I'm actually doing a month challenge to focus on my food and not weight myself at all. I'm measuring/weighing myself before and after. We get so stuck on numbers and not focus on how we feel. I'm trying that for once. I'm really in for the long haul, my old habits weren't healthy or helpful. I'm not counting calories so much either. More like a base number, and more on the healthy carbs. It's such a different way of life. But I'm loving it. I hope you see the benifits as well.