You've got to remember that while you are obsessed with the scale and the results you're getting, the way to a healthier body/keeping it there is replacing fat with muscle. So many women are terrified to lift weights because they think Masses of metal+Lifting=BULK. I promise that you will not become a body builder if you lift weights in moderation and do it properly. Would you rather be at your goal weight and still have a pooch and thighs that need firming, or finally have the body you've been working hard for and still weigh 10-15lbs more than your goal weight? I don't know about you but I'm going with the second option. So while YES it is discouraging to step on the scale and see you haven't lost anything or have even gained, keep track of your inches to stay motivated. (you WILL still lose weight if you exercise and eat right I'm not telling you that you will stop losing weight if you lift metal.)
Another thing I wanted to share with you that has helped me is the Live Strong website . If you sign up (it's free!) there are awesome features such as MyPlate which helps you track your daily calorie intake and will list all of the nutrition facts of the item you ate so you know whether you need more protein or carbs etc. You can also log your fitness routine which will keep track of progresss and inform you of how many calories you burned during the workout. There are recipes, success stories, fitness libraries, information on what foods are best for you and the list goes on! Seriously, go sign up and use the crap out of it!
I started out by needing to lose 78-80lbs in order to not be considered "obese" for my height and have reduced that number to 40. I can tell I've lost weight but at times it doesn't feel like it's been a significant amount and I get down in the dumps. But when I compare 80 lbs to 40...well it seems like NOTHING! Just keep reminding yourself that EVERY little bit counts! Stay focused and get back on track.