Hi Katie and welcome to DWD. You certainly have been through the mill recently. The come down from a wedding can certainly trigger depression. But you are doing the right things. I think at this stage you should make am appointment with the GP for yourself. They will be able to help and give you the support you need.
However in the meantime, you have come to the right place. We are generally a friendly bunch and always have a friendly welcome for newcomers. Have a look around and jump in when you feel comfortable.