You can always write a Larghissimo marking at the beginning if you see you're stuck with too little music
Ha, I do indeed have a two minute very slow introduction..........the entire first minute barely deviates from the note A flat.
A little update on the progress of the piece: I have finally come across an overall form that I like. What I am really trying to achieve is a natural progression from one section (as defined by the prominent textural and instrumental writing in each passage of music) to the next. The form is essentially just one idea which evolves into the next and continues to do so in a rather gradual fashion. All the while, some thematic material heard near the beginning of the piece holds it all together. I have called the piece 'Evolve' because I think it describes how the music happens.
EDIT: looking at an earlier post of mine in this thread, it seems as if my idea for the form of the work (the music going through different 'sections' in that gradually evolving way I described in this post) is the original idea I had for it anyway.