Fat Loss Apparent, but Scales Do Not Agree

1950 calories per day---lost 12 lbs. since Dec. 7th and exercise 5-6 days per week. The scales have not moved in 1-1/2 weeks, but I am exercising at least 1 hr. per day on the elliptical trainer and clearly losing fat all over (tightening the belt, face smaller, chest fat dissipating, etc.

What is going on? Will my actual weight start dropping quickly? Too much fluid retention? Too much exercise? Not eating enough calories? Building muscle and this is compensating for the weight stabilization? Confused and need advice from those who have experienced this. Thanks in advance for your help!!!