How do you stop getting too comfortable too fast in a conversation?

I have a problem of getting comfortable too fast with pretty much any conversation and sometimes making the person i talk to uncomfortable, i say things i really really shouldn't, within minutes i start acting like i've known this person for years, like i can talk about anything and this slapped me so hard when i was talking to this new person i met, as a friend. And something i said clearly made her uncomfortable and i feel so bad about it. Do i just think before everything i say? Do i work to make that into a habit? Do you think to put some distance first and try to be extra slow? Because i don't wanna make people uncomfortable obviously, but i also have a habit of speaking really fast and this would really change the way i communicate entirely. I just wanna hear some opinions.