I have to agree with trying to be controlling or jealous.
I am in a restart in my engagement with my fiance after 12 years. Because I used to be like that. But she was worth it. Find what's worth fighting for in her for you to calm down on the questions.
What helped me was a few things. Breathing, of course, normally. The more irritable whatever feelings you get, if you don't release that stress right away, you're going to come off as a sarcastic smart ass or pop. If you have those issues. Either way, it's going to expose your insecurities. Have faith in her and trust that she has her eyes only for you. We tend to trip up over second guessing ourselves or reading too much into things. It's not going to be easy to change your perception, but I swear to you, it will help you in this relationship or any relationship. Not many females want to be questioned about everything. Take you're time, and be honest, open, and direct. Don't be a prick about it though. You care for this person, show it. And not by that way.
We are posting this because we have also been there. In one way or another. If you are able to control this, it will be a blessing, if not, it will be an ill omen. I wish you the best.