misgendering trans male partner, need advice because it hurts him.

Hello, I am talking to a trans male and it's my first time doing so, for context I am genderfluid and pansexual so I'm queer myself. I have been trying my best but there's been a few small occasions where I've accidentally misgendered him in conversation, it usually doesn't take much effort for me to not do so but I'll have a slip of the tongue and it tends to hurt his feelings and it ends up in him requiring space for a bit. Despite my pansexuality, it is something I've barely come to accept within myself and my dating history is all female, calling a partner with masculine pronouns is something new to me. This is a fairly fresh relationship and I really don't want him to think I don't respect his identity or see him as a female. I've been doing exercises with myself to use the correct terms in conversation and have suggested recently me and him sit down and practice together so I know how to consistently put it to use in conversation but I want further advice because how much he means to me. Thank you all.