In multi-cell networks, coordination multi-point (CoMP) is an effective means to enhance received signal strength through joint transmission (JT) or null out undesired interference via coordinated beamforming. This work theoretically analyzes the performance of CoMP with both JT and interference nulling (IN) using stochastic geometry. To enable cooperation across cells, multiple base stations (BSs) are grouped in a cluster predetermined by the network operator, which we call the network-centric clustering. Due to the irregular topology of BS clusters and independent design of beamforming weights across different clusters, exact signal and interference distributions are difficult to obtain. To simplify performance analysis, previously work assumes either a regular topology of BS clusters or a certain scheduling mechanism in place to eliminate intra-cluster interference. In this work, we consider the irregular topology of BS clusters and allow the cooperating BSs to serve multiple users by JT and cancel intra-cluster interference through IN. We derive the coverage probability and ergodic rate of network-centric clustering. Numerical results are presented to validate the analysis accuracy and demonstrate the impact of key system parameters, such as cluster size, BS load, number of antennas, to the performance of the considered system.