S.H.
I think it is far too soon. My Dr. and Nurses told me to think of the "fourth trimester", the three months after the baby is born, as the time to work on my family and my bonds with my baby and not on myself. Has it even been three months since the baby was born? How do you even have time to run 8 miles a day with a baby in the house? The people in Hollywood can snap back because they have a nanny and a cook and a house keeper and a personal assistant and a trainer.
Have you met with a personal trainer? Usually a gym membership includes some training. It sounds to me like you are over doing it and your body is no longer responding. So it is true that the more you work out the less effective it becomes.
If you are looking for sympathy... I totally get it. I long for the days when my hip bones stuck out and you could see my ribs.
If you are looking for advice...Talk to someone about body image, it sounds to me like there is more to this story than you are telling us. My husband says he like me better now. Making love to me when we were first together was like humping a bag of rocks. Now I am this beautiful woman and my body was what nourished the lives we created together and no matter what I look like compared to what Hollywood says, he loves every part of my body for what we have done together.