Diet question. I'm so confused!

First, the essential info: 23, female, ~140 lbs. My goal is primarily fat loss, and I'd like to build muscle as well. In the past I've felt best about my body when I'm right around 125, but I also want to be more muscular so I'm trying to ignore the scale. Trying.

I've been using the LoseIt app to track calories and macronutrients. I usually hit about 40% carbs, 35% protein, 25% fat.

I'm confused as to what my diet should look like, and specifically how much I should be eating. On one hand, I feel like I should be eating at a calorie deficit to lose weight. LoseIt has me eating less than 1000 calories (net, subtracting calories from exercise) to shed the fat. I feel like this is way too low, but at the same time I'm worried about gaining if I eat more. (I'm typically not hungry throughout the day, unless I do a particularly hard workout).

On the other hand, I keep seeing things like "Gain muscle, it'll burn your fat! You need to eat more to build muscle! You can't cut fat and build muscle at the same time!" so I'm confused. The scale hasn't moved, the tape measure hasn't moved, I'm getting stronger but I still don't like what I see in the mirror.

TL;DR: I don't know how to eat. Help me out, ladies.