I'm so confused!!

This is not my first time on this weight loss merry go round. About 5 years ago, I lost 50 pounds with WW. I have since gained about 30 of it back and I am having the hardest time. First off, I don't like the new WW plan so I am trying to use mfp. I have 1200 calories as my goal. I do cardio kickboxing and am training for a marathon. Right now, my longest runs are only about 5 miles, takes me about an hour to do those. I do 3-5 miles 4 days a week, and cardio kickboxing 2-3 days a week. I eat when I am hungry, I am having a deficit on calories. The scale is barely/not moving. I lost .2 this week. I'm not sure what I'm doing wrong. I am not letting myself go hungry, I eat when I feel I need to. In fact, I thought I was doing pretty well. Here are my thoughts: Am I underestimating my calories/portion intake and overestimating calories burned? Am I eating too much and need to cut back? Am I eating too little and need to add more (honestly, I'm afraid to add calories.) Am I getting older and so losing weight is going to inevitably be harder? I've never lost weight while working out, unless it was strictly running. This is the first time I've done anything like boxing/kickboxing. It's mixed with a crossfit type circuit. It's pretty intense. Am I adding muscle and the scale will catch up? I have no idea what is going on. I know this type of question has been asked time and again and I've read and reread tons of it, so please don't be rude. I'm really looking for some honest help. I've opened up my diary, if you care to take a look. I'm 37 years old, female, 5'1, and 155.8 pounds.

Edited to add: I had fitness instructor friend who has lost 150 pounds tell me that her nutritionist said to ignore the exercise calories and focus on deleting sugar and unhealthy fats.