They dont go from being here every day to being nothing - because what ever your beliefs about after life etc including if you belive there isnt one they remain a part of you -they developed the person you are. your mum shares your genes,but it isnt just physical, she is in your heart and mind all the time, and at the moment in a way which brings you nothing but pain because physically she has gone.
In time you will start to replace that trauma with the best side of her.The moment we leave is just a moment in our lives and our lives are much more than just a moment. The things she said and did, some funny,some loving, some annoying at the time but which you can smile over later, the phrases she used that irked you when you were a teenager which you thought you would never say, you will, and if you have children or even be part of the lives of other people children. you will pass all of that on to the next generation, even when you dont realise you are doing it.
You will still seek of all her wisdom, you know what she would have said and thought,about a situation you find yourself in or decision you have to make, and i know its really painful right now and some times over the years it is more painful than others. I found myself crying over a xmas carol 14 years after my mum had died because it was a rarely heard one and i remember her trying to learn to play it for a school nativity play (she was a teacher) but when i finally stopped crying i went downstairs and learned it myself she is still teaching me just in a different way to when she was here. She isnt and never will be nothing the bond between us is still strong it has just taken a different direction i cant see her or touch her but she is always there.