Just need a little advice

Communication is what I need help with my fiancé. Idk why when something serious happens very small though ( example small misunderstanding in tone when asked something or he expresses himself to me ) I shut down like a kid being scolded. I tell him idk why I do it he thinks I have some type of trauma but I don’t I tell him I didn’t go through anything growing up anything I did as a kid/teen was my decision and I’ve learned and moved on from it. We got into this relationship both having kids him 1 and me 2, we have 1 child together and another on the way. We both agree we love each other and don’t want to end but I cannot get over communicating back to him. We have tried counseling with a pastor not a professional therapist or anything so I’m thinking we may need to go that route.

Literally communication on my part is our only issue everything else is fine. He fixed his issues he had a drinking problem and stopped and has been clean. I agree to fix my communication and no luck idk why I shut down