i know how you feel...i've now lost 2 stone 2lbs and only just starting to notice some results. i'm tall and a big build anyway and it seems to take a while for me to even drop a dress size, but i'm slowly getting there. i think once 3 stone has gone i will start to see a proper difference and drop a whole dress size. when i started i was realistically a tight 24 and a actual 26, but now i'm wearing 22's, 24's and 26's, although most 22's i try on don't fit yet which can get frustrating.
you probably haven't noticed much change as you wear quite loose clothing.