I’m sorry to hear that you are feeling so low.
You might be depressed (physically/psychologically) or you might be going through a period of spiritual dryness, as essentially all of the saints did at one time or another, or you might even be ignoring some third path you are called to take which some other concern keeps you from seriously considering. Ignoring calls is hard on the soul. It could be many things like that.
Feeling as if “things don’t matter” when you have many objectively good things going on in your life may be a sign of depression. It is certainly a sign that you should seek outside counsel and support…even Jesus had his Simon of Cyrene.
If you think you may have depression, please see a doctor about it. You have a moral responsibility to take care of your body. I get mild depression from time to time, and I find that a regime of getting more sleep, eating more carefully, and being more diligent about getting exercise is a duty during those times. It makes a huge change in my mood, which affects not only my spiritual outlook but how much others get out of being around me. I also tell my husband when I’m going through a hard time, and he is a great help. Some people have more serious depression, which sometimes must be treated with medications. Do not be too proud to accept medical help for medical problems.
Whether or not it turns out to be a physical problem, it would appear to be a spiritual one. Get spiritual guidance and support. Your pastor or spiritual director isn’t going to make it all go away, but they will help you to navigate it in a way that will add to, rather than damage, your spiritual health.
That is the main thing. “Gold tested in fire” implies that the dross gets poured off, that the extreme conditions endured were applied to achieve God’s ends. Treat this problem with diligence so that it does not negatively impact your ability to love or your trust in God. If you have to go through a dry period, at least do your utmost to make it a dry period in which you remained as faithful to your call as possible.
As for heaven, love God, love God, love God, and fear not. If you love and serve God, you can trust God to take care of eternal life for you, to protect you from all evil, and to never abandon you, no matter how dry and desolate the desert gets.