Absolutely, I think this is vaginismus! I had vaginismus and I’ve felt exactly the same way, even when using dilators with Maze to overcome it. It’s described as feeling like a ‘wall’ (it’s your pelvic muscles).
With time and practice, you can relax those pelvic muscles/get through them – you can get a tampon, dildo, dilator, etc. through successfully 🙂
I remember doing HUGEEEE deep breaths when I was using dilators while also being suuuuuuuuper slow when inserting. Sometimes it felt like the ‘wall’ slowly opened (but I’m not a medical professional so I don’t know exactly what happened and that could have been in my mind HAHA). Sometimes knowing that I did it before (inserted the dilator successfully) would help me relax and ‘open’ those muscles. Also using tons of lube was a game-changer for me 🙂
I hope this helps!