Give yourself time to grieve, because you need time. Maybe months, maybe a year or more. The pangs of grief come and go like waves, but now the only constant thing is exhaustion, because grief consumes a lot of your energy - it's like the equivalent of a grave physical illness. So don't push yourself to do anything, get as much rest as you can and try to avoid any additional sources of stress, major decisions, difficult projects. Sometimes, even browsing through her things or reminiscing can be unbearable, too much; sometimes, a friend or relative or bereavement counsellor can make you feel even more lonely, or angry, or discouraged - it's ok, you can reject or postpone anything that makes you feel worse.
To me, the only thing that was really helpful after I lost my mum, ten years ago, was journaling, but this happened only a year and a half after her death (I didn't have any counselling). This is how I understood that grief is so painful and exhausting because it is basically a mixture of intense fear and anger: we can't actually understand and accept death, the radical separation and loneliness that comes with losing a dear one, and this is frightening and makes us angry. It may sound obvious; but the fact that I understood this about my own grief, instead of being overwhelmed and unable to process those emotions, was helpful.
Later I remember feeling a small hope when I listened to a sermon - the priest said something like this: if we feel so sad, for so long, after losing a dear one, it just shows that our love for that person was strong and is enduring; love is stronger than death, your bond with the deceased is stronger than death. Then slowly I started to feel better, to see myself through the kind eyes of my mother (instead of blaming and hating myself for the bad things that I've said and done when she was alive) and to get used to this loneliness. Time only heals this sharp pain of grief, not the loneliness - but eventually you will find the power to cope with this loneliness.