I understand completely. I have a 3 month old. I started at 105 & got up to 115 when we had a second tri loss. Got pregnant right away & then put on another 40 lbs. I am down to 143 right now & it sucks. I've always been tiny & feel horrible. I hired a trainer & worked out for 6 wks while only loosing TWO pounds!!! I fired the trainer & am now doing it on my own--just trying to squeeze in squats, lunges, crunches, ect during DB's naptime. Also ordered a home stair climber to use during naptime as well. Started Lean Cuisine's for lunch also since I rarely have time to fix myself something healthy for lunch while taking care of the baby. Maybe you could try sometime like this as well? I'm learning that convenience trumps most things when it comes to taking care of the baby, so pre-made meals & equipment I can use at home seems to be easiest for me right now.
Good luck!! Hang in there!