It’s super annoying, but I have to track calories in order to lose with IF. The same may be true for you now that you have less to lose. Really I use IF as a tool to help me stay at/below my deficit calorie goal. Congrats on your success and good luck with the last 15!
The last 15 (in my case 20) was harder to lose than the first 105.
I had to use the same structure and fully eliminate sugar for a couple of months. It was not sustainable, it was just hardcore dieting.
So you’re good at fasting now, but you’re going to have to deal with even more austerity. You have to be hungrier and fight off hunger more often and consume fewer calories.
And if you can, work in some weightlifting of some kind. Make your body repair itself but don’t give it the easy fuel to do it.
If you haven’t eliminated alcohol yet - that’s usually the easiest way to reduce calories.
Volume eating (more fibers/salads) and more protein usually help too.
Counting each calorie for a week might be eye opening. Most people manage to underestimate the impact of random snacks.
And ultimate solution - up the resistance training, and focus on inches instead of pounds.