This is probably the least helpful thing I can say on the surface, but trust me, it will get better. Teenage years and the recovery from them were some the worst points of my life. When I was 17 and 18 I attempted suicide multiple times because life was that dark and hopeless. I felt that no one could ever love me and no one would ever listen. I felt I was broken and couldn't do anything right.
The thing is, despite feeling like that, I kept trying. I found a smidgeon of hope and refused to give up the idea that tomorrow might be better. Work on something you believe that you are good at - even if there is no recognition of it. Keep sharing and talking here, having a community that understands what you're going through helps so much. Maybe seek out some therapy and stick to it for a bit - at first it might feel a bit pointless, but after a while things will click into place. Losing a parent is one of the hardest things someone can go through, especially at 15-16. I have known people who completely fell off the functioning life train when that happened to them at that age. I really suggest, at the very least, seek out some bereavement counselling. Grief can last years and will have so many ripple effects... My thoughts go out to you.
I think, as stupid as it is, online dating (and metal music...) saved me somewhat. I kept trying, there were many setbacks, but eventually, I found the person who stuck by me even though he met me at one of my lowest points. You are special and there is someone out there for you. Having an interest you love also helps to build up self worth.
You are 19... So neurologically speaking your brain will still be going in an emotional overdrive... In a couple of years, as the brain matures those emotions will calm down. I felt the change at around 22-24. By 26 things affected me less. Don't give up. Take it one day at a time and you never know, tomorrow might be brighter.