Losing weight?

Hi all, I'm 21, engaged and have a year and a half old son. I'm a stay at home mom but do housekeeping once a week for a family near me and go to college. I gained a lot of weight during pregnancy and lost most of it. I gained weight everywhere especially my arms, stomach and thighs. I'm currently at 168lbs and 5'3. My stomach is where I have most of the weight. I have a lot of extra skin there. When I wasn't in school, I worked out 4-5 times a week but didn't see any changes and gave up. I've tried different diets many many times but I can't stick to them. Now I'm stress eating due to this very very hard class. I don't know what to do. My fiancee mentioned something yesterday and I've been feeling down ever since. Any advice? I want to weight around 130-135 lbs but I feel hopeless. I've had my thyroid tested and everything's normal. I'm having such a hard time losing weight. Any ideas on what I can do? I'm drained by the end of the day with school and my toddler and I can't find the energy to work out anymore. Help!