I thought it took 21 days (or so) to form a habit?

I'm pretty sure that the 21-day thing is just a myth. Here's a better researched answer, though: http://www.huffingtonpost.com/james-clear/forming-new-habits_b_5104807.html

I was in the same situation as you. I was so close to my goal weight (I wasn't trying to lose a whole lot in the first place, just around 10-15lbs). I started on January 1st, and I was at about week 5 as well when the junk food binges started. For me, it lasted an entire month. So all of February, I was binging every few days on junk food. I think if I put all the days that I binged together, in total, I must have binged an entire week (or maybe more) of February. It was really hard. I think you just have to come to the realization that you are the one in control. But of course, as always, it's easier said than done. I used to take naps, brush my teeth, drink a cup of black coffee or tea or just leave the room altogether whenever I felt like I needed to eat everything.

In retrospect, though, I wish I had decided to up my calories to maintenance and eaten like a regular person for about 2-3 weeks instead of trying to keep eating healthy or dieting because February was a very distressing month for me.

Also, for me personally, I was able to identify the two time periods that were really dangerous in terms of my binging. They were the hours between 3-5pm and then again between 6-9pm. So I started doing things at those hours that would distract me. For example, I started taking hour long naps from 3:30-4:30pm, and instead of doing morning workouts, I started going to the gym from 7-8:30pm. It took a while for me to figure this out, but ultimately it really helped me. I think you need to figure out those triggers (whether it be a certain time in the day or when you feel a certain emotion or whatever) and avoid those triggers by distracting yourself.

Now, I'm back on track, and yesterday, I was finally able to stop myself amidst an almost-binge-episode which was very triumphant for me.

Just keep pushing yourself forward. Don't dwell on the past, and keep telling yourself that regardless of what your mind is telling you, you are making progress, maybe slowly, but surely. Don't give up or lose hope!

You said you are really close to your goal, is it possible you need to bump up your daily calories a smidge? I don't know what you are set at, but if you are within 10-15 lbs of your goal and are losing more than half a pound per week, maybe reset to half a pound per week to give you a little extra wiggle room so you can ease off a little?

I have days every once in a while that I just have to eat more. I just aim to stay at my maintenance calories when that happens and get back to my lower goal tomorrow. Or ummm maybe the day after

I'd never heard the 21 days to form a habit thing before joining this site. I'm not sure where that comes from, but it has not been my experience. Habits can take various amounts of time to form for me, mostly based on how much I enjoy whatever it is.

And the thing about habits is they often take longer to break than form, especially if it is something I see as a chore.

When it comes to food I find it's more about changing my tastes/preferences than forming a habit. I mean, eating is a necessity not a habit.