I'm so sorry for your loss, I lost my mom last year aswell. I understand that feeling that things are out of place at the moment, you will feel ups and downs but I think it is necessary that you don't lost track of your life, I know it is something extremely hard to do, but if you work, study or have a hobby where you meet other people, keep doing those things, pick one at least, because that time where you are busy will be like some extra time for you where you are not constantly thinking about what happened.

Not everyone grief the same way, if it helps I recommend that you search for books about the matter, none of them will have all the answers but they will explain to you how grieving works and why everything you feel is completely natural. There will be times when you will remember her fondly and that is good. Focus on your healing and look for all the help you need. Take your time.