I don't really have a stutter, but I have noticed I've been pausing in the middle of my sentences because I forgot the next words that were supposed to come out of my mouth. What's happening to you could be an autistic trait.
there are comorbities with speech, and it's not definitely related to autism, but it for sure could be. Many autistic people have something called apraxia, meaning difficulty saying what they want to say. It happens to me a lot, so sometimes I'll be able to speak well, but other times I can barely force out two words. Theres also just difficulty with uncoordinated speech that can be common.