what is the most habit to acquire for constant weight loss

I second everything said here but would suggest you begin taking a sublingual B12 daily if you aren't already and since you sound like you are busy, busy, busy some weeks with little chance to cook, you need to find a way to have snacks with you at all times.  That way even if you don't have time to cook all the time, you'll still have healthy, hopefully high protein snacks with you when you need them.  You may also want to try cooking in bulk and portioning out single servings so even when you are busy, you just need to grab and go, no muss, no fuss.

Good luck and hope your energy comes back soon. 

thanks to all of guys for all of your enriching replies