I struggled with this for a long time as well. It helped me to remember that how I felt or what I was thinking would not ever change the truth. God knows your heart and sympathizes with your struggles. We may never "feel" like we are saved 100% of the time, but we can choose to put our hearts in His hands. Hope this helps.
I’m not certain of your particular tradition/denomination but I have read some very interesting theories that suggest that Martin Luther had OCD - some of what he’s written on his salvation doubts and how he dealt with them are very interesting and appear to me to be a Christian approach to “sitting with uncertainty” - I’d look it up (as long as you don’t do it compulsively ;) )
I've read about this too. Just avoid taking to heart Luther's original strategies of self-punishment and constant confession. His compulsions were very intense. 😬 His writings about his struggles are very interesting though, and provide some great insights. Today I think we would say he struggled with scrupulosity and religious OCD. I'm pretty sure he wrote about how (later in life) sometimes he chose to be a little unscrupulous at times on purpose "to keep the devil from gaining a foothold." I always found that strategy comforting. OCD is obviously an illness that can be helped by clinical treatment, but for believers it's good to remember that the enemy would like nothing more than for us to believe every lie it throws at us. When we choose not to it's a form of spiritual warfare bc we know who is the father of all lies. I find that empowering.