Loved the story, very suspenseful and well executed. I agree with other commenters that maybe adding more actions while waiting would keep players more engaged, could be subtle things that dont really affect the story, like switching lights on or off or stuff like that. Heck, the character doesn't even really need to react to them, it's just something else to do while waiting.
But I really enjoyed the slow burn, really great stuff for your first horror game, congrats!