Could you try sticking to low GI foods? If you are getting the shakes it might help to eat foods that are slow to break down (e.g. dairy foods like yoghurt or tea with milk, whole grain breads, low fat cheese and crackers, porridge for breaky...) If you google low GI foods you will probably come up with loads of suggestions online.
The excersise is brilliant That's going to be the best way for you to get healthier quicker.
But I just want to reassure you, it's only 2 months since you had a baby! Don't be too hard on yourself, I'm sure you will get to where you want to be weight-wise in time. Take care