To me it sounds like the majority of the problem is in your head if not all. People don't seem as bothered by your smell as you are. I've noticed a few coughs or sniffles etc... every once in a while means nothing. It's just when you get it a lot that it matters.
If those few coughs and sniffles are all you've gotten you don't smell. One thing that's helped me is think of what you would do if someone smelled really bad. If people do those things that you wouldn't do if someone smelled then you're prob over thinking things.
Another thing is think back on from the time you started thinking you smell til now. Think of all the people you've been around and things you've done. If people seemed relatively okay being around you then you're okay.
I don't know about you but for me there's always this fear that I may have been okay before but now I smell. Do you think like that too?