Since you are already at a healthy weight for your height I suspect that's why you are not losing large amounts of weight. With that said, a couple of suggestions...
Are you eating enough fat? It has been shown that higher fat in = higher fat out.
Also remember you can lose inches without losing pounds, this is normal and happens to everyone. Stalls are normal, they are your body's way of shifting gears and figuring out what changes are happening.
Again, 5'8 and 149 lbs is a perfectly healthy weight and I can't see it would be very healthy for you to lose much more. Just keep at it, and if you have weight to lose, it will come off, but the less weight you have to lose the slower it will be...if your in the last 5 lbs to lose, i reiterate, it can take some time for that since your body is more likely to hold onto it. Maybe try an Atkins fat fast if that's your goal?