Plateau

Hi

With under a stone left to lose (to my first goal at least) I hit a plateau about 3 weeks ago. I was eating approx 1500 calories a day at this point. After reading the forums I decided to calculate by BMR/TDEE,

My BMR is 1409
TDEE 1747(20% reduction)

I have been sticking to the TDEE as closely as possible (sometimes being a tad under) for the past 3 weeks and still no movement.

I am 5"5 and 149lb.
Exercise - I walk 4-5 miles a day, 5 days a week (brisk walking). Spin for 2-3 hours a week.

Any advise how to break though it would be much appreciated.

PS I have lost almost 6 stone to date.