weight after baby?

ok after my first baby which is almost 2 next month I lost over 20lbs after I had her. I was depressed wasn’t eating and so overwhelmed. I was never able to gain it back.. I got pregnant with my second who is 8 months in a few days and I breastfeed full time. I gained all of that 20lbs back while pregnant with her and when I had her dropped right back down to the other weight.. i’m so annoyed and idk how to get it back on track.. I was 137 before them and dropped to 115 which is my current weight right now.. and I’m so unhappy with how I look. is it true breastfeeding burns tons of calories?