Kudos on the fitness streak.
One thing that helped me immensely was getting my VO2 max tested. This is similar to a stress test with a breathing mask -->
https://en.wikipedia.org/wiki/VO2_max
It's a measurement in cardiovascular fitness so while I wanted to lose weight, I was so out of shape, I could barely work out. My first VO2 test was a 27! An average male for my age would be 35-39! As an example, Lance Amstrong's VO2 max was an 86.
I use a Polar M400 with chest strap, the past 2 weeks log has my VO2 @ 34 so I've improved 7 pts in 11 months, dropped 22 lbs in weight (and 2 sizes in my jeans).
One thing about the test that I liked is it provided me witha print out of target heart rates with calorie burn rates. So instead of guessing or calculating the calorie burn for 80%, 90% and 100% heart rate I used the data on the printout on my Polar M400 fitness tracker. So when training, it's not about the HIIT counter or speed but rather keeping my heart rate in the optimal zones for the most efficient burn.
It works for me and it's not an expensive test if your medical doesn't cover it (which it should but hey, check first).