Holga panoramic close up

A panoramic view of a bookshelf. This is the 1st roll I made with a new pinhole panoramic Holga. I expose this twice the time a Sekonic exposure meter reading because it don't give a f number higher than 90 and the "specifications" of the Holga manufacturer is that the f number of the pinhole is "137". I found the neg a little bit thin. Could the thin condition be product of a reciprocity failure not given, the film-development combination, not enough development time?. Some advice, please