P90X3 and stubborn fat loss, is my nutrition right?

Frustration: Difficulty losing stubborn fat and trimming down the last 10lbs since having 2 kids, ages 6.5 and almost 4 yrs now.

Exercise routine over the last years: 4 x/week on average, if I’m lucky 5x, consisting of 2 runs 6-10K (one hilly trail, one flatter road), and 2 x 1-hour sessions of HIIT /cardio/strength with personal trainer with weights (mainly 15lb dumbbells).
 
In an effort to switch things up and hopefully get over a hump, I started P90X3 Classic 6.5 weeks ago (weights 15lbs on average). Following program every day and enjoying the variation (so 6 workout days, 5 p90x3 doubling up one day, to allow for 1 PT HIIT training session and 1 rest day with Dynamic stretching), and 1-2x a week adding an extra workout in to make an hour. Also doing 1-2 runs in addition, hilly trail 9K, and/or road 6-9K.
 
Progress: seemed to lose 2.5 lbs in first 2.5 weeks on P90X3, 123 lbs to 120.5 lbs, so was pretty excited, but then went up to 121.5 lbs and stayed around here. Been reading around for nutrition advice, for everything I read there is something to slam it – try low carb, try high fat, try more protein, more carbs ….. so confusing. I realize there is a diet for everyone but real extremes would be almost impossible for me to manage shopping, cooking and managing with a travelling husband, two small children, and full time work – and I’m not convinced that this is the answer as for as many people that say it works, there are as many that say it doesn’t. I don’t eat junk food, home cook almost everything, rarely drink more than one glass wine per week and exercise hard so its very frustrating.
 
Age: 37 (just), height 5 ft 1, (initial weight 123 lbs) weight ~121.5 lbs, TDEE ~2,000, so from previous posts taken advice and been eating 1700 calories(tracking on MFP) and playing about with carb/fat ratio but keeping protein at 30%. I eat every 2.5-3 hours with protein 25-30g every sitting. I have recently in the last week put this up to 1800 calories (35% carbs, 30% protein, 35% fat) wondering if I need more calories instead but no change still. When I ate less, about a year ago, people said I wasn’t eating enough to lose the fat and the body was storing it. Trainer says fat should be 10-20% of diet, and carbs much higher, …. But from what I also read its better to have more fat and less carbs.
 
Anybody else been stuck in a similar situation and any advice that might work? It seems I can’t win despite trying so hard. Husband made less effort than me and lost 25lbs in the last 18 months, doesn't track calories or nutrition and drinks quite a lot of booze, grrrrr!

Thanks for your advice, I do realize there are many posts just like this :-)