You've done amazingly well so far. Don't be so hard on yourself dude. This doesn't have to be your Everest. Worst thing you can do is feel bad about things, go into it with the wrong mindset and force-starve yourself. I'm sure that's how a lot of people end up dying from this.
It's been a great experience & experiment but with an active lifestyle, it can't be too good. Especially with a HR of >100 at the airport! Keep in touch with your guide and please don't be a martyr. We need you bro! ;)