Thanks for your message and welcome to the forum.
Firstly, let me give you a bit of an insight into the male psychology when dating. When men are with their lady, it's absolutely imperative that they feel completely exclusive. They want to feel unique, special and in a way that only they can make you feel the way that you do. Anytime this isn't felt, their sense of masculinity and self worth is dramatically impacted. Hence, when other men smile at you or you give off any sort of indication that you are interested in other men, this will spark him.
Now in terms of his behaviour, there's no doubt he will be a little more sensitive to your behaviour given your past actions. From what you are saying, it doesn't sound too much like you are interested in other men - you just have a lovely energy about you and like to smile and so on. However, it's important that you recognise the impact of it - which it sounds like you do.
What I am curious about though is - do you work hard at making him feel like the most special man on the planet? Does he know how happy he can make you? It's absolutely imperative that he understands this at a deep level so he doesn't have any fears that you will end up going off with another man.
As for you being oblivious to your behaviour, have you asked him to provide you with specific examples as they occur? The more evidence you can get, the more awareness you have of it. One thing I will say is - if you are just simply giving off a kind smile to both men and women, then quite frankly, it's his issue to deal with. That might be blunt, but you can't suppress an important part of you just because of his jealousy. However, I do believe in boundaries and it is important that you aren't engaging in behaviours that are somewhat crossing the line when you are in a relationship.
Hope that all makes sense.
Any questions, please let me know.