New Mama, New Member, Old Problem

Hello! I am new to this forum/website/app. I am a new mama (my littlest daughter is 4 months old) and I have a 5 year old. This is not my first jog around the weight loss block. I am having a lot harder of a time with it this time around though! I am 28 years old (29 in a few weeks! Yikes!) and am currently about 205lbs at 5'6. Not exactly were I want to be! I am a small build so according to my doctor 125-135 is a healthy weight for me- I am shooting for 130 and I will see where I get but 75lbs is a long way to go! OMG I didn't realize it was that much! I won't go into the whole story but a depressing and hateful first marriage brought me from 118-171 and then I had my first daughter- up to 223...hard work brought me down to 165, back up to 190, separation brought me back down to 168, new relationship and too much baking - back up to 185, pregnant with second daughter, up to 226 and then now I have lost 20 lbs or so of that baby weight and am now stuck at 205 again. My first goal is to get back to 185 so I can consider this baby weight gone, then 170 so I an consider all of my baby weight gone lol but I am lost here. I hope this works!