How to stop TTc

Ok so I’ve been trying now for 18 months for baby #1 and miscarried twice. It’s emotionally destroying me. I love my fiancé but only want sex when I’m fertile feel very horny that week then it goes away, I still give him it when he wants but it doesn’t bother me wether we do or not. It’s all I think about, I’m constantly on here checking everything I just want to stop. I don’t want to prevent it by using bc but I just want to leave it be until it happens but I can’t stop thinking about it every single month. Please help.