Sending you a welcome hug, S.
No one can ever replace your mum, but she will never really leave you, because you will carry all the memories she left you, all the love you shared and all the strength and inspiration she gave you in your heart for the rest of your life.
I know how much this hurts. I came here too after losing my mum about eighteen months ago now, but, as someone who is a little further along in this ordeal than you, I assure you, it does get better, even though I know you can't imagine that ever happening at the moment.
All you can do for now is to try to make sure you remember to eat and drink and take it one day at a time. The loss of your mum is a huge shock, no matter how prepared you may have thought you would be, knowing it must be coming. Nothing ever prepares you for such a blow and recovering from this will take you a very long time, but we are here for as long as you need us. We have all suffered different losses who have found our way here, but we all go through the same experiences and emotions and understand one another's struggles with this terrible time.
You are not alone, S. Sending you strength and a huge hug..