lost over 100lbs, need to lose ~25 more, lost all motivation

Hi there. I'm a 29 year old woman who, over the last year and 8 months, has lost about 113lbs. I lost 100 last year, and have been stuck where I am for about 4 or 5 months. I've lost motivation, and keep yo-yoing between 164-170. What works, food-wise, for me to lose in the past doesn't work anymore. I can get down to 164 again by netting 800 calories, (eat 1400, work off 500 according to FitBit) but that's hard to keep up. My problem now is that I want to eat on plan for most of the week, then go insane (and I am phenomenal at eating bad.) On plan for me just means within calories, but I do try to eat balanced overall.

Has anyone else been in this situation? How did you pull through? I am considering hiring a personal trainer through my University (I'm a full-time grad student, teach, and have a second job, so I'm stretched pretty tight, but I've been overweight my whole life and want to be in the "normal" bmi as a 30th birthday present to myself this December.) I know that will help my fitness, but will it help weight loss? And I am anxious over a trainer that will tell me to eat only chicken breast and salads (if I can't eat everything in moderation, I will binge like mad.)