I think if your goal is to drop the bodyfat and not worry too much about muscle mass, you can take a small deficit approach to dieting and make lots of gains (losses). However if you are seeing a stall out or a drop in energy and you've been running at the cal deficit for a while (e.g. several weeks... months) then I'd suggest exploring some possible carb ups or upping the total cals a bit or something to recharge your body. It is now burning at a great rate but its probably gotten used to running on the lower cals. We talk about a rule of thumb of 10-12x your bodyweight to "maintain" - more like 12-15x for specifically building muscle. You may want to look at your muscle mass now or soon and consider if you are losing muscle mass as well. You can change the ratio of bodyfat to lean muscle mass by increasing your muscle mass as well as by dropping fat.
If its all still working for you, you may want to just keep running w/ it as you are, but there's a stall out point where what has apparently been working great may not be optimal anymore.
... this leads into the ongoing state of change that occurs when you realize the freekin' amazing things your body can accomplish once you get past a lot of self-sabotaging myths and fad diet approaches and accompanying feeling of helplessness or failure related to dieting. As you are seeing, its literally life-giving. There's no end to the things you can see yourself accomplishing now. But a tough part of it is when you hit those goals, do you chose to stay or to go further? Change your goals? Or what? As Daisy noted, going below 15% can be a hard thing to maintain unless you are very specifically teaching your body to operate at a lower bodyfat. You may find it lifestyle restricting after a while. Another note - you've seen what you can do, and you are probably thinking I'm going to live this lifestyle (e.g. the tight diet, training, etc.) every day of my life. I'll never stop it. That's fine, but you will also pass thru some phases of accommodation where you will want to take a break from it or just plain old get sick of the gym or the diet & need a break. It happens to EVERYONE. Sometimes life gets in the way - case in point - me. I was going to do 2 major competitions this year but first I started having lots of joint problems, then I was going thru a whole pile of stress waiting for a job offer to come thru, then I started working at the new job, got roped into working literally 80 hrs in my 3rd week (including late nite and all weekend), then I got sick and now I'm traveling. Suffice it to say I haven't been in the gym in 3 weeks at all, and sporadically since this summer. I needed the break to heal and just to deal w/ other crap that I had to deal with. So now I've got a different goal of getting in the gym, also focusing specifically on fat loss & also mass loss since I probably won't be competiting in BB anymore.
Anyway -- just trying to point out the "long view" - once you get addicted to the lifestyle it is so liberating but it can also take its toll on your regular life (which you may not think is a bad thing now) but it will become critical that you find a balance that you can live with. This comes w/ time, but just think big & long. Go for different goals. Learn how your body responds to different stimuli - e.g. changes in your diet - more protein, carb rotation, cal cycling, different sorts of training, etc. Its a whole new adventure, but you'll see your body constantly going thru small swings in response to the different things you experiment w/. Just "getting leaner" and perpetually fighting to get your bodyfat down to some number that is really only in the realm of competitors just isn't a good goal so think outside of that to how you look and how you feel, vs. a number that is sort of irrelevant in the big picture. You can start to self-fuck when you find that you've passed your goals of bodyfat and your body starts to slow down and the "getting to a lower bodyfat" really isnt' the right goal and you start to see possibly even gaining some bodyfat back, etc. (Sorry I'm getting long winded...) -- just take it as you go and live in the moment.