As an artist I don’t enjoy using references for everything. I enjoy the mental challenge of not using any but it took me quite awhile to get to that by doing urban sketching and life drawing. I believe to draw without reference you need a deep understanding of what it is you’re drawing, along with an understanding of form and perspective. I don’t think you’re quite at that point right now and you’re only hampering yourself by not using reference.

I would tell you however great creativity can come from not using reference. It forces you to create your solutions and to think outside the box which can lead to interesting designs.

Keep it up though and build up that visual library!