exercise and weight loss.

Hi Brooke,
I have lost 50 pounds over the past year. Over the past 6 months I have fluctuated within ten pounds. I would like to lose another 20 pounds to get to the mid range of my BMI.
I have a protocol I am pretty solid on during the week days. I exercise with a trainer 3 times per week and usually walk 5 miles on the other days. I go for a long bike ride 1-2 times per week on date night. In short I have been building a lot of muscle. My clothes still fit perfectly. I have the opportunity to join the master swim class 3 mornings per week from 6-7 am.

The question is whether I join the Master swim at that time. I wonder whether all this exercise is inhibiting my ability to lose weight. I am enjoying how strong I feel. would it be better to use this resource (time) to journalling and really getting to 100% with nutrition. Does one activity really have anything to do with the other, should I do the Master swim and ALSO refocus on the journalling and nutrition?