Mom with a very low self esteem

Everything start when I have my first child and after I give birth I start to gain weight, my last relationship end after 9 years and he left me for another woman, that makes it worse, I don’t feel beautiful and I feel very fat. Right know I am in 134 lbs and I want to go to 120 or 125, I eat healthy and I exercise 3/5 days of the week. I don’t know what to do else because I still in the same weight, I drink a lot of water and I don’t eat on fast foods. Please a little help in here. Thanks