If you have the funds, get a babysitter to take your DD out for three hours on a Saturday morning, maybe to an organised activity + park + lunch. I know it's probably the last thing you want to do when your DD has just started school but if it's 10- 1pm for example, she gets a lie in, and some activity, to tire her out for the afternoon.
DH and I had to do this for a period of two months when I was recovering from an operation and it really gave us a massive break during a stressful period. And because it was on a Saturday, and we could rely on it, and look forward to the break, the benefit felt like it was longer than three hours if that makes sense.
Failing that, maybe put her in a dance or gym activity for an hour on a Saturday morning and your DH do the drop offs and pick ups or you do it together and have a coffee out somewhere while you are waiting?
And could someone in your extended family help on a Sunday (or a friend if you don't mind telling them about your depression)?
Either way, a set structure at the weekend really helps when you are struggling
it takes a bit of discipline to set up and a bit of team work, but it is worth it.
As for your depression in general, it's great that you are doing things to help yourself recover. Please be encouraged that all the latest research about brain plasticity means that you can recover, you are not stuck with it for life, and brain chemicals can affect your behaviour and the reverse is true too. 