The general rule is - one page of a properly formatted screenplay equals one minute of screen time.

In your post, it seems, you have put in staging and blocking where actors movements and camera movement are mentioned. Normally, a writer doesn't put in these things as it's like - you're directing the film on script.

However, it seems you are making your own film & have nobody to impress and that's fine.

Below are few suggestions:

• How you open the film & where main title & end credits appear, that time also counts & would extend the screen time.

• You should give some breathing space for background music in scenes. Which means transitions, cuts from one scene to another.. it may be rapid cut, fade or dissolves. This depends on your pacing. Yet, all of edit would increase screen time

• Pacing of dialogues - every character will have their own way of speaking dialogues and newcomers would realise at edit table that film which was supposed to be 10 minutes has extended to 15 minutes of screentime. So, you should be extremely careful to rewrite the whole dialogues by actually reading the script & recording audio in your voice to get an estimate of screen time.

Do the aforementioned and you will have an idea where your script stands .. and, best wishes to you and your team.