I know exactly what you are going through hun .... the whole reason I compiled the list of hints and tips is because my little lad went missing about 7 years ago. At that time I had absolutely no idea what to do. I posted him as missing on a couple of cat forums and I received so many words of encouragement and tips on things to do. The main tip was posters and flyers. I actually thought my world had stopped when he didn't come .. I couldn't stop crying and was devastated like you.
The only thing that kept me sane was my new "friends" on the forum .... they knew how I was feeling and didn't make me feel like a fool for crying over a missing cat (something alot of my non-cat owning colleagues at work seemed to think).
Thankfully my little lad was spotted 7 days later by a lady who had seen one of my posters. She phoned me and told me where he was last seen, I immediately drove round to the location and called him. He was hiding round the back of the old folks home under a huge bramble bush. As soon as heard me calling him he came out and jumped straight in the car ... he was as pleased to see me as I was him.
It was at that point I decided to put all the useful hints I had been given into a list. Over the years more ideas have been added and the list in now pretty comprehensive.
I think the thing I found hardest to cope with was the feeling I wasn't doing enough and there must be something else to try. I hope you find the ideas help you and I will keep everything crossed that your handsome lad is back home very soon.
Remember you are now a member of the Purrs family and we are all here for you if you need us.