I'm sorry for your loss, OP. My parents have both died and I miss them every day.
There are two questions really, one about how sad you feel and one about the language you use to describe it. How sad you feel, how much of a loss your mum is to you, is entirely personal and for nobody else to judge or compare or minimise.
But words are supposed to mean things, and speaking purely on the language issue, I do find that words like "tragedy" get cheapened and become meaningless when they're used to describe events that "very sad" would do for.
I would describe the death of an elderly person by natural causes or accident related to age as "very sad", the death of a child or teenager as "devastating" and certainly a personal tragedy for the individual and his/her family, and the death of many people in a violent atrocity or a large-scale natural disaster, as "a tragedy."
If the death of anyone, at any age and from any cause is considered "a tragedy", then it becomes about things being more tragic or less tragic or beyond tragic. What's the point of that? Tragedy isn't the only word.