Regarding the theme, I suggest you take a step back and pinpoint exactly what you want the audience's takeaway to be. As it stands, I can't tell if this story is about ancestry, mental health, domestic violence, etc.. It's okay to have multiple themes, but it would help if you chose one theme to focus on, then work the rest of the story around it.
From a technical perspective, here are a few notes:
- When introducing characters, I recommend you show rather than tell. In other words, don't introduce Joana by writing that she has "an open, honest personality". Briefly describe her physicality to introduce her, then show us her open/honest personality through her actions and dialogue throughout the story.
- I don't think you need to break this up into acts. It's only 14 pages, so the three act structure seems unnecessary.
- The dialogue sounds a bit unnatural. Maybe try speaking them out loud as you write? It might help determine whether or not they flow naturally.
- On page 9, I would delete the lines "And for the next ten days, life was a breeze. Nelson and
Joana enjoy togetherness like teenagers jacked up". Stick with describing events as they happen. You want us to see your short film, not read it like a novel. Saying they were happy for 10 days is information that we can't visualize in the moment. There are a handful of descriptions like this throughout your script that need attention.
Hope this helps.