Stick with me. I'll get around to an answer in a sec.
Pinhole photography does strange things to film/paper. The Law of Reciprocity states that a specific amount of exposure is attained with a specific intensity of light and a specific duration of exposure. And if one is changed then the other must be changed to an equal degree if the same overall amount of exposure is to be attained. When a photon strikes a silver halide it converts it to a proportionate degree into black metallic silver. This is what happens during exposure. With a normal photographic lens and normal (more or less) lighting, this is usually acheived with shutter speeds between, say, 1/30th of a second to 1/1000th of a second. Even down to 1 full second the Law of Reciprocity is still in effect.
However, outside of a certain range of exposure duration (usually published by the film's manufacturer) the Law of Reciprocity begins to break down. It dies this because as the further exposure duration moves from this range the more silver halides lose their developable capabilities. Two things are required to reverse this effect. EVEN MORE time and then more developing during processing.
I said that to say this. Don't take it to Walgreens or anyone like that. Find a real lab or a photographer near you that can work with you and knows how to process film that was exposed through a pinhole. Your average techy probably has no idea what a pinhole is unless his blood is coming from it.
Oh, and the April issue of the magazine is going to be a pinhole issue. Thought you all would like to know that.