You are doing great man! Keep pumping it up and don't get discouraged when you have bad or weak days; it comes with the job so to speak.
If I may give you a tip, since you mentioned that you are taking a low carb approach on your diet - and since we don't really know what low carb means to you - but something that will help you regain your strength: every 48 hours have one high carb meal whether it's lunch or early dinner (before 6 pm). This will help you regain momentum for the rest of the days that you are limiting your carb intake. Your body is using up it's glycogen stores with your intense workouts and HIIT so this will force some much needed carbs right back where you need it: into your muscles. But be sure to stick to high quality clean carbs such as brown rice, yams, red potatoes, quinoa and accompany that with a little broccoli. As to how much carbs? Well, it depends on how much you can eat. I'd say eat start at 120 to 150 grs of carbs and always add a little protein with this also (about 25 grs). You will take advantage of the insulin transport you just stimulated and you'll feel the difference for the next few days.
Be sure to drink your water bro. Try this and let us know how it goes!