I just keep gaining

Ever since I stopped nursing my daughter when she was around 8 months old I have been none stop gaining weight. I was closer to my pre-pregnancy weight right when I stopped nursing my daughter than I am now. I have been trying to lose weight since the beginning of summer but nothing is coming off. Instead of having just 10 lbs to lose to be back down were I was at before I got pregnant I now have 40 lbs to lose. I do not know what happened! I have also been a stay-at-home mom since my daughter was born, she is 2 now. I have always had a job before her so I know that I am not as active as I use to be. I do workout and I have cut back on some things in my diet. Now I really need to buckle down on losing weight before I get to out of control.