Is it common to frequently regress back to the bargaining stage of grief?

It’s been exactly a year and a half since my Mom passed. I’m 25 now. For the first year I was extremely distraught but kind of in “survival” mode so I don’t think the full magnitude of grief really hit me.

For the past month or so, I’ve found myself really grieving it hard. I’m functional but my work performance and attention to detail is suffering and I’m very preoccupied with sad thoughts.

Most notably I find myself having a lot of thoughts like “I would give ten years of my own life for just one more year with my Mom.” or the dreaded What Ifs? like “What would have happened to my brothers and I if she’d died when we were kids.”

Worst of all is the fact that while I’m angry at her for so many things, I also miss her terribly. :’(

These thoughts (and others) are extremely upsetting, cause me to lose sleep and make it hard for me to focus. It’s been so bad that a couple of times my boss has brought it to my attention which makes me feel terrible and fear for my career. If I lost my job due to this, I don’t know what I would do and fear it would drive me over the edge to hurt myself.

Is this normal? What should I do?