Poppy, just seen this thread, and do hope that you are now involved in getting back at work and have some support from your work colleagues.
You really do need to allow two years to mourn the loss of someone so close to you. Time -does- heal, but a lot of time.
I was 43 years old when my beloved Mum died. I was busy with hubbie, and six children, but still found it took me a long time to even start to recover from that loss. Three months after her death I found myself actually walking into a shop, as I had seen something in the window which would be ideal for her christmas present!!
Your Dad is also desperately trying to deal with his own loss, and (like so many men) not willing to admit to how he feels.
Do not be afraid to talk about your Mum to everyone and anyone......Each person has to deal with mourning in their own way. When my youngest child died suddenly at the age of 25 all I wanted to do was to talk about him BUT only to people who had known him. I refused Counselling as I knew it would not help me. Even twenty years after that death, I still want to talk about him to people.
Your family are probably very concerned about you and trying to work out ways to assist you. They are not being intrusive, just trying to help and support you. Let them know of the best way they can do that -even it means saying you need some time out from them.
Just remember that your Mum would have so wanted you to LIVE the rest of your life, so the best way of honoring her memory is to try to that.