Plateau making me miserable!

It's been six months. For five months my weight dropped and dropped. I've lost 4 stone and I'm about a stone to a stone and a half away from where I'd like to be (which would still give me a 'bmi' of 26!) Nothing has changed, I've been increasing the dose. I'm still eating much less, walking every day and yet I'm completely stuck. I've been hanging just above 12 stone for weeks and it's sooooo frustrating!! I suspect it's just because I've dropped so much weight so quickly my body is just having a pause but it makes no sense.

Do I just wait? Do I try and do something?