Hmm, the only idea I have is that, since you have relatively low BF to begin with, you might want to consider lowering carbs even further, like below 50g. Try just walking maybe 30 mins every day and lifting something heavy, i.e. no running or biking. I don't think it's always less exercise=less fat burn. Because if you're exercising a lot, your body starts to think times are hard and starts storing fat.
Anyway, that has been my experience with it. When I first started PB at 5'2" and 125lbs, I was not overweight by any means, but had fat to lose and muscle to gain. I aimed to keep my carbs under 30g and was able to see immediate fat loss.
Everything in moderation, including moderation.