Very well done on losing all that weight, it's brilliant
The great thing is, is that you haven't gained back any weight. I think it's understandable to go through periods where you just get a bit tired of a plan when you've been sticking to it so well. I think it sounds like it is the right plan for you, it's just finding your way back to being motivated again.
I had about a year (bit more I guess) where I just stopped doing Slimming World, gained about 2 stone back, but am returned and really want to finish what I started this time. I personally find seeing inspirational stories of others managing to get to target really help, so when I am feeling a bit rubbish about it, I seek those out. I think it's finding what works for you to get you motivated again.
Maybe give yourself small milestones to aim at, it can be a bit demotivating to see the whole picture at once. I think once you start to see good losses again it might spur you on.
Wish I could be more helpful, but you have really done an amazing job with your losses so far, you can definitely do this.
All the very best