Have you had a medical opinion on the make up of your midriff region? I don't necessarily mean a costly scan, but someone who knows?
For a loooong time, I thought, despite being a scrawny old bird, that I still had some fat on my midriff until I was discussing the prospect of a post surgical Coleman graft. The nurse almost fell off her chair and declared that region to be prett well fat-free, but maybe the skin just wan't as firm as on other area of my body (I other words, my skin there hadn't been elastic enough to cope with my skinnying up.).
I've spoken about this a bit on the forum from time to time, but I never carried an awful lot of weight, but I had always had more of a straight up and down shape, looking from the front or back, and it was some time after I was maintaining weight that I noticed the appearance of a definite waist. Despite remaining at the same weight for almost 4 years now, about 2 years ago, I went from a size 8 trousers/skirt to a size 6.
Clearly only you can decide what to do and how you approach it, but I might be inclined to encourage you to just focus on maintaining your current weight, withing a range you feel comfortable with (+/- xlbs/kgs) and see what happens. Sometimes our bodies just take a little while to finish redistributing our "assets" after a period of weight loss - particularly when that loss is rapid. When we're losing quickly, we rarely lose it from the places we'd really like to, but it's a bit odd how it all catches uo in time.
Good luck whichever approach you decide. You'd had an incredible journey so far.