Exercise motivation, and nutrition question, please

Hi! My name is Angie, and I'm at the end of my 12 week program with a goal of about 23 lbs, and only meeting half of that. And haven't lost inches or lbs the last three to four weeks (week in the middle I did pretty well on the calories! As I was on a seven day cruise and maintained). My problem is I can't keep the nutrients balanced, sugar fat and protien. I'm concerned about how it effects my calorie count trying not to go over carbs sugar or fat and still get my protein, without going so low on my calories. I do ok on most maintenance days, one or two a week. I feel I'm learning much, but obviously not enough. Any ideas for finding the right balance?
My main reason for posting is because I haven't been able to motivate myself to do the training. In the whole 12 weeks I did the training 3x's. I am sure that if I had trained I would of come closer to my goal. How do you get yourself started and keep going. Especially if your like me with not a athletic bone in my body, ever. And I'm 49 years old. However any words of advice would be appreciate your time, as I already do for taking time to read my very long post.