using nursing as an excuse to...

hello, i have been eating more late at night lately and everytime i tell myself that it's ok b/c i am breastfeeding. it si not okay and i am at my heaviest weight, i know it is b/c i ate salty foods yesterday, but i am in the 140's and i am already 4 months pp. i am at 143 that is so high, the worst part is that i don't think i look terrible. i want to be down to 125-130. help me i need advice. i am exercising for a good hour a day but i am eating when the kids are in bed...HELP