I've just been in an extreme lean phase prior to moving into a bulking phase, I needed it, I needed to shed body fat from late night snacks and crappy overall diet on the run.
I'm "basically" following the initial phase of the P90x program taken a bit to the extreme and since I have not hit a "bonk" and I've had the energy to continue, I've kept it there and kept shedding the lbs.
My typical diet includes instant oatmeal for breakfast, protein drink mid-morning, turkey or roast beef on whole wheat roll with mayo and lettuce for lunch (no chips or anything else), then protein shake mid-afternoon, then usually mahi, grouper or cod with a bag of either steamed broccoli or green beans, then a protein drink right before bed.
I've really gotten used to this diet and it's working, but know I will need to re-introduce red meat, lots more chicken with egg white omlets and turket bacon.
I think I can adjust my diet and eat the required protein/carbs/good fats and meet the 3k plus calories goal and I no longer have any bad eating habits, so it's just upping everything I'm already eating and introducing more red meat and chicken along with good carbs.
on some days I will substitue the turkey for chicken and even more rarely I will substitute lean roast beef and I will also throw in pasta 3x a month or so for dinner instead of fish, but I really love fish.
If your diet is really as clean as you say then your in good shape. You cant overlook the power of homeostasis though. You body will adjust to survive and that means famine as well. If you cut cals too much for too long your bodies metabolism will slow down. Thats why when dieting its always recommended to shoot for just a couple pounds a week to try and avoid your body from slowing its metabolism.
In addition to that use workouts that offer prolonged fat burning benefits like HIIT/tabata cardio or simply do xfit workouts, they will have you burning fat for up to 24 hours after a workout which P90x just isnt gonna do.