E.T.
Going to the gym will make you feel better. You will shed weight and exercise releases endorphins that make you feel good. Also, my gym has a nursery that is only $2, while you work out.
You need to start carving out some "me time" which should bring down your stress and depression.
Your son is only 9 months. You are in this for the long haul. You need a sustainable routine and it doesn't sound like your current one is that.
BTW, you don't say it, but in my experience, when I am rushing around too much, I usually don't make good food selections. If you can't make it to the gym, resolve to make healthy eating choices. Fresh fruit, non-fried, non-packaged meals, etc.