Gaining weight is simply taking in to many calories!

Maintenance calories are when you eat and don't gain or loose weight.
When you eat to many calories your body gains weight.
when you eat to little calories your body looses weight.

Are you counting calories you eat each day?

I think your carbs are the enemy, not your fat intake!

try reducing your carbs by 10% for a week and see if your weight
continues to go up? prefferably the late night carbs.

Your body doesn't require the same amount of cal when your not on AS.

Or instead of dropping your carbs, add some cardio to your daily routine. Either way your reducing your total # of calories per day.

Hope this helps!