Trying to loose 11 more pounds and having a hard time!

Hiya,

I've started logging on MFP a few weeks ago, but discovered the forums only today!! I'm 5ft7 and 139 pounds (171cm and 63kg) and I want to bring it down to 128 pounds. In terms of BMI I'm not overweight, but I just want to get fitter, and replace some fat with muscle. I'm finding it sooooooo hard though! I have lost 11 pounds (5kg) since January (I know, it's absolutely nothing compared to some of you who lost over 50 pounds during that time! - Well done by the way!!). The last few weeks I haven't lost more than 1 pound per week. Although that's exactly what MFP recommends me to do, I'm finding it extremely demotivating to loose weight this slowly, and at times it really brings me down. Does anyone have any advice or do any of you perhaps have similar experiences? Many thanks in advance! :)