I think I would be constantly wiped out and sore if I did HIIT on top of sprints and lifting, too. I just do lifting 2x a week and sprints 1x a week or less, take a hike on the weekend and take easy walks at lunch for sunshine the rest of the time. This doesn't get me to reduce fat at all, but that's not a priority right now. Someday I'll do HIIT in place of lifting, but for now I'm not very strong and my focus is to change that. The Primal Blueprint Fitness book shows lifting and HIIT as interchangeable. One or the other, but not both. Doing both probably runs the risk of overtraining. Anyway, if you think you aren't focusing on strength right now, you might try prioritizing the HIIT instead of lifting and see if that can budge some of your more persistent fat. I've also heard that you can just do a 5 minute "finisher" thing after lifting to try and budge the weight. It's kinda like a mini HIIT session but without any rest between exercises. Honestly I do not have the energy for such a thing after lifting. It's a struggle to walk back to my office sometimes.
As a persistent endomorph (I've even got photos from childhood to prove there's a difference between non-fat endomorphic me and my ectomorphic little sister), I don't really believe that anything other than concentration-camp-like eating regimens is really going to get anymore weight off me. I hiked the Pacific Crest Trail and even hiking 30 miles a day I never got any thinner than I am now.
Female, 5'3", 49, Starting weight: 163lbs. Current weight: 135 (more or less).
Starting squat: 45lbs. Heaviest squat: 180 x 2. Heaviest Deadlift: 230 x 2