Not sure whether I have a stutter

Not sure whether I have a stutter For the past couple of months I noticed that when speaking with new people I frequently get stuck on certain phrases, commonly starting with sounds like "ah" or "uh." It feels like some sort of mental block. Usually I kind of just work my way around it by rephrasing my words but it's annoying. I'm able to talk fine out loud alone and I wouldn't say I have anxiety, though I do get nervous. What do I have and how can I fix it?