My boyfriend and I are both FtM while we got together as female. At the moment, I'm still mostly living as female (school/at home) but my boyfriend started as a guy at school this year. Since we onyl came out to our friendgroup this summer, the first few days/weeks of school were
very confusing to him, as you may imagine. And still, everybody thinks he's a bit deaf 'cause he always takes some time to react to his name.

Right now, I've gotten to the point that, in my head I will think 'he' or 'him' about a 100% of the time. While when I'm talking to my folks, I still have to say 'her' because they have no clue yet. And to our friendgroup it's confusing, because he hasn't asked them yet to call him by his new name and use the right pronounce. (we and our friends live quite far apart so we don't talk that often)
I feel that, in my head, gender and pronounce are hardly connected anymore 'cause of it. Because I need to switch it around so often and all. I know I'm a guy but because I'm 'she' to the outside world, I tend to think in those terms. My boy sees me as a man though.
Let's just say pronouns are a habit. Nothing more, nothing less.