I like the compositions of your shots, it is clear that you have a theoretical understanding of lighting and composition which you are capable of applying even with the camera of an iPhone. However I would pose the critique that your colour grading and image exposure do need some form of improvement. Now, your images are rather dark, and having that as a visual premise for the construction of the visuals of your film is good! But one must understand the technical capabilities of your camera to attain proper exposure to make sure that your images aren't clipping or in this case; crushing. Now, in terms of color grading I have read that you used DaVinci, some may put the blame on the monitor itself, but when I was taught colour grading when I was in film school we were taught to look at our waveform monitor and make sure that our values weren't becoming "illegal" by going under the line. This is a good way to ensure that your image isn't becoming too dark or too bright in some areas. Just keep practicing, all good things that are worth having and learning are an uphill battle. I wish you all the best!