How to Lose Last 20lbs

I have been on a diet (LCHF- low carb high fat) for about a year now, and have lost 75+ pounds. I've decided to join the military, but I am 15 lbs away from the required weight. In a perfect world I would hope to be below that, but I can't even get there right now. Anyway, I've been trying for months and months to get the scale to move and it will not. I've tried fasts, all the way from IF to just 5 Day long water fasts. I've tried putting myself into a massive calorie deficit followed by extraneous exercise. Everything I lose following those plans, I gain back just as simple. I eat in a calorie deficit already, and I work out 6 days a week doing things like HIIT, cardio training, and running (~2 miles at a time). I have been to all the blogs and even a personal trainer and haven't found anything that works. I understand weight loss is a slow and tiresome journey, but I really just need to meet my weight requirement so I can get on with my life. Literally any help or advice you have would be great! I'm at such a loss here.