The investigation of the dimension of Bergman spaces has long been a central topic in several complex variables, uncovering profound connections with potential theory and function theory since the pioneering work of Carleson, Wiegerinck, and others in the 1960s. We investigate the dimension of p-Bergman spaces associated with pseudoconvex domains in \(\mathbb {C}^n\) , particularly focusing on the case \(p\in [1,2)\) . By constructing \(L^p\) -versions of the extension theorems of Ohsawa and Ohsawa–Takegoshi, we establish several geometric and potential-theoretic criteria that ensure the spaces are infinite-dimensional. The range \(p\in [1,2)\) is imposed because for \(p>2\) , classical tools like Ohsawa–Takegoshi and Skoda become unavailable or lack suitable analogs. Sufficient conditions for the infinite dimensionality of p-Bergman spaces of complete N-circled fibered Hartogs domains, weighted p-Fock spaces are obtained by applying the mentioned \(L^p\) -analogs of extension theorems and generalizing a sufficient condition of Jucha. We also obtain sufficient conditions for triviality of p-Bergman spaces of balanced and complete N-circled fibered Hartogs domains with one-dimensional base.