Get 250g of protein per day spread out over 4-5 meals. Whey protein can be used to help you out here. Creatine is something you should be doing. You shouldn't do HIIT until the end of LP OR if you're obese, which you aren't, you just have been eating incorrectly for a bit.
I'd have a 2 servings of starchy carbs (rice and potatoes are a decent option) pre and post workout, and vegetables at all other meals. Stick to single ingredient foods and have enough milk so that you're gaining 1-2lbs of BW per week.