For goodness sake step away from the scales. Your body weight can naturally fluctuate by several pounds from one day to the next and even over the course of a single day by up to 4lbs. So weighing yourself daily does you no favours. As you've found, if it shows a gain you feel crap and will be more likely to go off plan because "after all what does it matter if you've already gained". Weigh in once a week only, and only at class if you're a member.
I agree do not weigh yourself every day just do it at class or once a week otherwise you will become obsessed. Good luck.