no such thing as spot reduction, when you lose weight you lose it from everywhere, not more or less from any one spot.
as for your stomach, try to remember that its the most critical area us men look at.
odds are that you have lost fat from your gut, just not enough yet for you to really notice.
even using a tape measurer can be deceiving because you could be building up ab muscle underneath, so your waist stays the same even though there is less fat.
the other thing to remember is that as you lose fat from other parts of your body it makes it harder to notice the fat you've lost from your belly. because everything kind of stays in 'proportion' - so you feel like you still look the same.
another thing is that you can lose belly fat but the skin hasn't tightened up yet. so it still looks as big, but its a mushier looser fat. once the skin tightens then it looks smaller.
anyway, all you can do either way is to keep dieting / exercising. if you go 2-4 weeks without losing any weight, then change up the diet or your exercise routine.