Why wont my heart accept the existence of Allah (swt)?

I spent the first 19 yrs of my life just kind of accepting that i was here and not really thinking about how or ever really contemplating the existence of Allah. About two years ago i was afflicted with a tragedy in my life and subhanallah i became very close to my religion only to find out later that that is what Allah sends out these trials in our lives. So for the past two years i have been gaining knowledge at a steady pace but even with all the lectures on islam that i have watched and all the quran that i have read i still have a hard time accepting the existence of Allah 100 percent. I do believe in Allah and i pray 5 times a day alhamdulillah but i dont have the certainty and that is what im really looking for. I feel like i have to constantly remind myself that Allah exists instead of just my normal state of mind being that Allah does exist and live my life that way. The only thing i can think of is that the first 19 years of my life has left such a dark layer over my heart and iv only gotten rid of some of that layer so i cant fully accept Allahs existence 100 percent