Frustrated

I have been loosing the same 10 pounds for over 3 years. I am so frustrated today. I have been working with a personal tots of rainer for 4 weeks. We have been doing circuit training with lots of core work. I was down 3 pounds the first two weeks but now I am up 4 pounds. I am so frustrated. I know I know you are building muscle but it still stinks. I am not sure what else to do. I am going to try to do more cardio work but I am not sure how I am going to fit it in to my schedule. i just want to be healthy and at a reasonable weight. I will continue to watch what I eat and see how that goes but damn it I have been working so hard. I thought I would see some differences by now. I guess not :(