I wanted to start this out by calling this "our" mind because of our similarities in how we think about things. It seems that in my experience, no matter the culture, the area of the world you live in, or different upbringings, there is a similarity to being human, we are all controlled by our interpretation of events. Your interpretation, as fueled by the tragic experiences and chronic illnesses, is painting life a different color for you and it is time we start noticing it.
Death is inevitable, yet still very sad. Losing someone is difficult, especially when we don't even get to wrap our minds around it. You lost your mother, and depending on your outlook on the afterlife, that can be a permanent loss. Often in these times, hope is found in spirituality, beliefs of heaven, and how we have eternal souls that never die. I have my beliefs, and it allows me to speak from a place of peace, but depending on your outlook, you might not see the same thing. It's cruel when we feel someone was taken from us, and then it is difficult to live with that loss, among other things.
Your chronic illnesses are a lot too. The fact that they are chronic tells me that you are accustomed to living a certain way, and maybe in times like these, they became that much more apparent.
Look, these things you mention, the things you notice and think, they are all very real. Strength is not found in the unreal, but in what has happened and how we feel about it, not in how we sometimes think we SHOULD feel about life. Often when working with people I notice an underlying belief when they are suffering, I notice there is this measurement they compare to, something else they SHOULD be feeling, they think. On the contrary, pain is really the only guarantee in life, and yet we have been told, and we believed the lie that it shouldn't be.
We have more negative emotions than positive ones, and when stressful situations occur, we are equipped to deal with them because of the negative emotions. However, angst isn't about the emotions, but our pressure to get over them, to feel happy, that there should be some alternative life for us. Your life is the one that you have been given, and it can be the greatest life there is, with the loss, with the pain, unless you choose not to see it that way. Unless you let grief and the negative consume you.
Much of life is spent in our heads. Do not walk through this situation interpreting these events as something that detriment you. You have the choice with what you do with life; no matter how hard it gets, you can choose to see the good, the beneficial, or at least the positive things. You have the choice not to give up your thoughts to the circumstance. The emotions will come and go; let them pass. Let grief hit you like a wave; it will pass. It is the thoughts and our belief that this will never end, or the expectation to be better, that actually plagues us. Otherwise, what is wrong with the way you are handling things now?
Remember, you have thoughts; they are provoked by circumstance. You are not these thoughts. You can practice noticing them so they can float on by, and you can find purpose and value in all this. I am not saying that is the goal, but it may be the way to transcend all the inevitable pain. Talk things out, get heard, and have the person you are talking with listen. You can fall in love with life again if you see the parts you can control and take hold of them.