Could be related to sleep deprivation. I am a LOT less fluent after just a normal instance of not sleeping well, and my understanding is that being a new parent basically equals constant sleep deprivation. I'm sure the huge adjustment to a brand new person and the sudden change of schedules and routines also doesn't help! You're doing great, and I'm sure your speech will get back to a comfortable level of fluency as you settle into the routines of parenthood. <3