Son, I'm 41 and have been watching horror since the age of 4. I'm right up there with you in the number of horror movies I have seen. Some indie horror titles such as "The Hills Run Red" or the French made "Frontiers" and "As Above So Below" genuinely surprised me being better than initial expectations while others in the vein of "Flesh for the Beast" or "Bleed" were so bad they dumbfounded me. I have dove into the works of Dario Argento in my quest to broaden my horizons.
I have different taste than you and I'm very critical of horror because being a real fanatic I expect so much more. I will say this movie had a lot of promising elements, but I felt the acting was stilted enough to be unconvincing. It was the execution where this film fell apart along the way in its presentation, particularly the time jumps between reality and the fantasy of her safe haven in her own mind. When I figured out what was really happening midway through I was severely disappointed and thus the reveal lacked conviction and impact.
This is one Indie title which didn't work for me. I'm glad you liked it, I truly am, and that's the beauty in difference of opinion. However, I just feel someone whom has seen a lot of horror, more than some arbitrary claim, should have seen major plot points miles away before they were revealed. Also, said person should realize this very same premise has been done many times before and in a much better fashion. I'm just saying.