Interesting and impressive. In New Zeland filmmaking there is constant debate and complaint about the lack of funding from the Film Commission (since we're a small country with a tony industry, its hard to attract investors, so local productions often rely on govt funding). Granted, budgets are small, but when I hear people talking about their tiny $1 million budget, i dream of all the possible films i could make with that. Your film (granted ive only seen the trailer) seems to surpass the quality of these higher budget (so called no budget) productions. As someone aiming to shoot a feature in the next five or so years (I'd like to have one under my belt by age 25), it's a nice to know people can make good films with tiny budgets.
Not that I think having a small budget isn't at all limiting in terms of stories you can tell, crew and actors you can attract, etc - I just think some filmmakers tend to use their small budget as an excuse for poor quality.
Sorry for going off on a tangent there! But there you go op, you can do pretty grea things with few people and little finance.
As for making a film entirely by yourself, it would be difficult, but interesting if you pulled it off. Here are some suggestions:
1),If you're comfortable acting, you could write stories with only one character (or experiment with *other* characters-eg ghosts, doppelgängers, etc) and shoot yourself on a tripod. To make it visually interesting you'd have to have strong shot composition, and/or play to the style of having still shots, oorr, shoot in 1080p and add some movement in post (then export in 720p).
2) start shooting other things. Nature, cars, people on a sidewalk, bugs in a forest, etc. find a story in the real world through observation, or construct a new story out of these images. Look into observational documentary (such as the work of Frederick Wiseman) and maybe try experiment with something new in the format. You could always do other modes of documentary. Maybe something like the photographer who does "Humans of New York"?
3) animation. It's time consuming, very difficult, and hellishly frustrating. But I think it's a lot of fun, and stop motion films were my first experiences constructing films as a kid. You could do it through digital animation (when I was really young, id draw thousands of slides of stickmen skateboarding in PowerPoint and play them back quickly to form a "movie" - you could of course look more into stuff like blender and flash and so on) or stop motion type stuff.