Our bodies are really funny - I never lost x amount per week. It was always, 2lbs one week, 1lb the next, 0 the next, 3 the next, etc. Hang in there! Have you tried food journaling online with fitday.com or dailyplate? It really helped me to accurately count my calories and not eat too much or too little.
As for carbs, there are so many different opinions on how much is too much or not enough. A good start might be to limit them to 1 serving with each meal (1/2 brown rice, quinoa, oatmeal) and try to keep them whole-grain instead of processed (they're better for you and will keep you full longer). Plenty of people lose on higher carb, lower protein diets as well. It's all about calories, really. I try to stick to a 40/30/30 balance at each meal (give or take a few %, I'm not strict about it)- 40% carb, 30% protein, 30% fat. An online journal like dailyplate can help track that.
http://www.livestrong.com/myplate/
Good luck and ask more questions if you need to! 20lbs is AWESOME!