ok...here's my perspective from a guy who used to be extremely thin and fit, up to morbidly obese and then bounced weight around a bit:
1)
You can do it..you've done it before, so have the confidence that you can do it again/keep it up.
2) Don't beat yourself up too much. The first time I lost a ton of weight (from 300 to 225), I was super strict with myself, allowed myself no simple pleasures (food, alcohol, etc), and had an extreme exercise regimen. That can't last, so when I let go, I really let go, and blew back up to close to 280. If you keep a more relaxed attitude, your progress may be slower, but it is more likely to be more permanent.
3) Be aware of how your job can affect your metabolism. Any job that requires hours and hours of sitting
totally fucks your metabolism. It's one of the reasons why patrol cops, bus drivers, computer programmers, teachers, etc, tend to start swinging heavy after a while.
4) You're gonna have weight swings. It's natural. Especially for women, who can carry a wider range of water weight. My wife used to get hung up on if she gained a pound or two in a week. It took her a while to stop stressing about it. It doesn't help that the time of the month that women tend to carry more water weight is also the time of the month when they're more emotionally fragile.
5) Try not to stress.
Stress can cause weight gain. Also, as you mention, it can cause emotional overeating.
6) This is a pretty common time for weight gain, between the double whammy of holidays and winter. I gained about 12 pounds between Thanksgiving and Christmas, and I'm only just now a pound shy of where I was before the holidays.
A lot of places say you shouldn't weigh every day, especially because of point #4 above, but I find that I personally do better when I
do weigh every every morning. If I'm up a pound or two, even if it's just because of water retention, it helps remind me to quit slacking off on my portion control, salt intake, etc, and I tend to be extra vigilant. I just don't let it destroy me emotionally when it happens.
It also helps that since my wife and I are both have to goal of being more fit, we can talk pretty regularly about what's going on and help support each other if we slip, or give each other kudos when we hit new milestones.