Topic: luteal phase length

Hello ladies, I was just wondering if it was normal to have a usual 14 day luteal phase and then one month have a 16 day luteal phase. I KNOW I'm not pregnant so that wouldn't be an explanation but I was wondering if it was normal for it to fluctuate by a day or two. I always thought it should be the same every month so I'm not sure if I should be concerned or not (don't want to worry unneccesarily) Any advice you can offer would be greatly appreciated so thank you in advance. Good luck to all still trying and congrats to all who have been successful!