*shrugs* Bump it up to whatever intensity makes you feel like you are not going to want to do any other exercise after the HIIT session. For some people 10-11km for 30 seconds oso cannot tahan. Since you are obviously more fit, you have to make it more challenging. Remember to not hurt yourself though.

I don't understand what you are asking? If you want to determine your body fat %, the cheapest way is to eyeball it (You can post a picture here and the experienced sifus can help give you a rough idea). Otherwise, there are electronic scales, calipers, scans, etc. Besides a DEXA scan (which I am not even sure is possible to find in Msia) all of these are estimates. The best are calipers to measure your body fat (handled by someone experienced otherwise results are skewed too) as they have a 98-99% accuracy rate. You might call around to doctors, or sports centers to find out if there is someone who can measure you. My suggestion is eyeball it, make sure your diet and training is on point to maintain max muscle, train-eat-sleep, don't stop until you are happy with your body. If you find yourself too thin, too bulky, too whatever - Stop, reevaluate, determine new goals, readjust training and nutrition, continue.

It isn't complicated. You don't NEED supplements, or meal timing, or a gym, or a training partner, or a book. Just common sense, a plan, determination and patience.

Keeping it simple and sustainable is the best advice anyone can offer.